TOP248F-TL - Power Integrations, Inc.

Figure 1. Typical Flyback Application.

TOP242-250

TOPSwitch-GX Family

Extended Power, Design Flexible,

EcoSmart, Integrated Off-line Switcher

April 2005

Product Highlights

Lower System Cost, High Design Flexibility

• Extended power range for higher power applications

• No heatsink required up to 34 W using P package

• Features eliminate or reduce cost of external components

• Fully integrated soft-start for minimum stress/overshoot

• Externally programmable accurate current limit

• Wider duty cycle for more power, smaller input capacitor

• Separate line sense and current limit pins on Y/R/F packages

• Line under-voltage (UV) detection: no turn off glitches

• Line overvoltage (OV) shutdown extends line surge limit

• Line feed-forward with maximum duty cycle (DCMAX)

reduction rejects line ripple and limits DCMAX at high line

• Frequency jittering reduces EMI and EMI ﬁltering costs

• Regulates to zero load without dummy loading

• 132 kHz frequency reduces transformer/power supply size

• Half frequency option in Y/R/F packages for video applications

• Hysteretic thermal shutdown for automatic fault recovery

• Large thermal hysteresis prevents PC board overheating

EcoSmart – Energy Efﬁcient

• Extremely low consumption in remote off mode

(80 mW at 110 VAC, 160 mW at 230 VAC)

• Frequency lowered with load for high standby efﬁciency

• Allows shutdown/wake-up via LAN/input port

Description

TOPSwitch-GX uses the same proven topology as TOPSwitch,

cost effectively integrating the high voltage power MOSFET,

PWM control, fault protection and other control circuitry onto

a single CMOS chip. Many new functions are integrated to

reduce system cost and improve design ﬂexibility, performance

and energy efﬁciency.

Depending on package type, either 1 or 3 additional pins over

the TOPSwitch standard DRAIN, SOURCE and CONTROL

terminals allow the following functions: line sensing (OV/UV,

line feed-forward/DCMAX reduction), accurate externally set

current limit, remote ON/OFF, synchronization to an external

lower frequency, and frequency selection (132 kHz/66 kHz).

All package types provide the following transparent features:

Soft-start, 132 kHz switching frequency (automatically reduced

at light load), frequency jittering for lower EMI, wider DCMAX,

hysteretic thermal shutdown, and larger creepage packages. In

addition, all critical parameters (i.e. current limit, frequency,

PWM gain) have tighter temperature and absolute tolerances

to simplify design and optimize system cost.

PI-2632-060200

OUT

TOPSwitch-GX

CONTROL

OUTPUT POWER TABLE

PRODUCT3

230 VAC ±15%485-265 VAC

Adapter1Open

Frame2Adapter1Open

Frame2

TOP242 P or G

TOP242 R

TOP242 Y or F

9 W

15 W

10 W

15 W

22 W

6.5 W

11 W

7 W

10 W

14 W

TOP243 P or G

TOP243 R

TOP243 Y or F

13 W

29 W

20 W

25 W

45 W

9 W

17 W

15 W

23 W

30 W

TOP244 P or G

TOP244 R

TOP244 Y or F

16 W

34 W

30 W

28 W

50 W

65 W

11 W

20 W

28 W

45 W

TOP245 P

TOP245 R

TOP245 Y or F

19 W

37 W

40 W

30 W

57 W

85 W

13 W

23 W

26 W

22 W

33 W

60 W

TOP246 P

TOP246 R

TOP246 Y or F

21 W

40 W

60 W

34 W

64 W

125 W

15 W

26 W

40 W

26 W

38 W

90 W

TOP247 R

TOP247 Y or F

42 W

85 W

70 W

165 W

28 W

55 W

43 W

125 W

TOP248 R

TOP248 Y or F

43 W

105 W

75 W

205 W

30 W

70 W

48 W

155 W

TOP249 R

TOP249 Y or F

44 W

120 W

79 W

250 W

31 W

80 W

53 W

180 W

TOP250 R

TOP250 Y or F

45 W

135 W

82 W

290 W

32 W

90 W

55 W

210 W

Table 1. Notes: 1. Typical continuous power in a non-ventilated enclosed

adapter measured at 50 °C ambient. 2. Maximum practical continuous

power in an open frame design at 50 °C ambient. See Key Applications

for detailed conditions. 3. For lead-free package options, see Part

Ordering Information. 4. 230 VAC or 100/115 VAC with doubler.

TOP242-250

4/05

Section List

Functional Block Diagram ....................................................................................................................................... 3

Pin Functional Description ...................................................................................................................................... 4

TOPSwitch-GX Family Functional Description ....................................................................................................... 5

CONTROL (C) Pin Operation .................................................................................................................................. 6

Oscillator and Switching Frequency ........................................................................................................................ 6

Pulse Width Modulator and Maximum Duty Cycle .................................................................................................. 7

Light Load Frequency Reduction ............................................................................................................................ 7

Error Ampliﬁer ......................................................................................................................................................... 7

On-Chip Current Limit with External Programmability ............................................................................................ 7

Line Under-Voltage Detection (UV) ......................................................................................................................... 8

Line Overvoltage Shutdown (OV) ........................................................................................................................... 8

Line Feed-Forward with DCMAX Reduction .............................................................................................................. 8

Remote ON/OFF and Synchronization ................................................................................................................... 9

Soft-Start ................................................................................................................................................................. 9

Shutdown/Auto-Restart ........................................................................................................................................... 9

Hysteretic Over-Temperature Protection ................................................................................................................. 9

Bandgap Reference .............................................................................................................................................. 10

High-Voltage Bias Current Source ........................................................................................................................ 10

Using Feature Pins ................................................................................................................................................... 10

FREQUENCY (F) Pin Operation ........................................................................................................................... 10

LINE-SENSE (L) Pin Operation ............................................................................................................................ 10

EXTERNAL CURRENT LIMIT (X) Pin Operation .................................................................................................. 11

MULTI-FUNCTION (M) Pin Operation .................................................................................................................. 11

Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 14

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins ...................................................... 15

Typical Uses of MULTI-FUNCTION (M) Pin ........................................................................................................... 17

Application Examples .............................................................................................................................................. 20

A High Efﬁciency, 30 W, Universal Input Power Supply ........................................................................................ 20

A High Efﬁciency, Enclosed, 70 W, Universal Adapter Supply .............................................................................. 20

A High Efﬁciency, 250 W, 250-380 VDC Input Power Supply ............................................................................... 22

Multiple Output, 60 W, 185-265 VAC Input Power Supply .................................................................................... 23

Processor Controlled Supply Turn On/Off ............................................................................................................. 24

Key Application Considerations ............................................................................................................................. 26

TOPSwitch-II

vs.

TOPSwitch-GX

.......................................................................................................................... 26

TOPSwitch-FX

vs.

TOPSwitch-GX

....................................................................................................................... 28

TOPSwitch-GX

Design Considerations ............................................................................................................... 28

TOPSwitch-GX

Layout Considerations ................................................................................................................. 30

Quick Design Checklist ......................................................................................................................................... 32

Design Tools ......................................................................................................................................................... 32

Product Speciﬁcations and Test Conditions ......................................................................................................... 33

Typical Performance Characteristics .................................................................................................................... 40

Part Ordering Information ....................................................................................................................................... 46

Package Outlines ..................................................................................................................................................... 47

TOP242-250

4/05

PI-2639-060600

SHUTDOWN/

AUTO-RESTART

PWM

COMPARATOR

CLOCK

SAW

HALF

FREQ.

CONTROLLED

TURN-ON

GATE DRIVER

CURRENT LIMIT

COMPARATOR

INTERNAL UV

COMPARATOR

INTERNAL

SUPPLY

5.8 V

4.8 V

SOURCE (S)

DMAX

STOP SOFT-

START

CONTROL (C)

LINE-SENSE (L)

EXTERNAL

CURRENT LIMIT (X)

FREQUENCY (F)

5.8 V

1 V

IFB

LEADING

EDGE

BLANKING

÷ 8

HYSTERETIC

THERMAL

SHUTDOWN

SHUNT REGULATOR/

ERROR AMPLIFIER +

DRAIN (D)

ON/OFF

SOFT

START

DCMAX

VBG

DCMAX

VBG + VT

OV/UV

VI (LIMIT)

CURRENT

LIMIT

ADJUST

LINE

SENSE

SOFT START

LIGHT LOAD

FREQUENCY

REDUCTION

STOP LOGIC

OSCILLATOR WITH JITTER

PI-2641-061200

SHUTDOWN/

AUTO-RESTART

PWM

COMPARATOR

CLOCK

SAW

CONTROLLED

TURN-ON

GATE DRIVER

CURRENT LIMIT

COMPARATOR

INTERNAL UV

COMPARATOR

INTERNAL

SUPPLY

5.8 V

4.8 V

SOURCE (S)

DMAX

STOP SOFT-

START

CONTROL (C)

MULTI-

FUNCTION (M)

5.8 V

IFB

LEADING

EDGE

BLANKING

÷ 8

HYSTERETIC

THERMAL

SHUTDOWN

SHUNT REGULATOR/

ERROR AMPLIFIER +

DRAIN (D)

ON/OFF

SOFT

START

DCMAX

VBG

DCMAX

VBG + VT

OV/UV

VI (LIMIT)

CURRENT

LIMIT

ADJUST

LINE

SENSE

SOFT START

LIGHT LOAD

FREQUENCY

REDUCTION

STOP LOGIC

OSCILLATOR WITH JITTER

Figure 2a. Functional Block Diagram (Y, R or F Package).

Figure 2b. Functional Block Diagram (P or G Package).

TOP242-250

4/05

Pin Functional Description

DRAIN (D) Pin:

High voltage power MOSFET drain output. The internal

start-up bias current is drawn from this pin through a switched

high-voltage current source. Internal current limit sense point

for drain current.

CONTROL (C) Pin:

Error ampliﬁer and feedback current input pin for duty cycle

control. Internal shunt regulator connection to provide internal

bias current during normal operation. It is also used as the

connection point for the supply bypass and auto-restart/

compensation capacitor.

LINE-SENSE (L) Pin: (Y, R or F package only)

Input pin for OV, UV, line feed forward with DCMAX reduction,

remote ON/OFF and synchronization. A connection to SOURCE

pin disables all functions on this pin.

EXTERNAL CURRENT LIMIT (X) Pin: (Y, R or F package

only)

Input pin for external current limit adjustment, remote

ON/OFF, and synchronization. A connection to SOURCE pin

disables all functions on this pin.

MULTI-FUNCTION (M) Pin: (P or G package only)

This pin combines the functions of the LINE-SENSE (L) and

EXTERNAL CURRENT LIMIT (X) pins of the Y package

into one pin. Input pin for OV, UV, line feed forward with

DCMAX reduction, external current limit adjustment, remote

ON/OFF and synchronization. A connection to SOURCE pin

disables all functions on this pin and makes TOPSwitch-GX

operate in simple three terminal mode (like TOPSwitch-II).

FREQUENCY (F) Pin: (Y, R or F package only)

Input pin for selecting switching frequency: 132 kHz if

connected to SOURCE pin and 66 kHz if connected to

CONTROL pin. The switching frequency is internally set for

ﬁxed 132 kHz operation in P and G packages.

SOURCE (S) Pin:

Output MOSFET source connection for high voltage power

return. Primary side control circuit common and reference point.

PI-2724-010802

Tab Internally

Connected to

SOURCE Pin

Y Package (TO-220-7C)

1 C

3 X

2 L

5 F

4 S

7 D

P Package (DIP-8B)

G Package (SMD-8B)

R Package (TO-263-7C)

F Package (TO-262-7C)

1 2 3 4 5 7

C L X S F D

Figure 3. Pin Conﬁguration (top view).

PI-2629-092203

Input

Voltage

CONTROL

RIL

RLS

12 kΩ

2 MΩ

VUV = IUV x RLS

VOV = IOV x RLS

For RLS = 2 MΩ

DCMAX@100 VDC = 78%

DCMAX@375 VDC = 38%

For RIL = 12 kΩ

ILIMIT = 69%

See Figure 54b for

other resistor values

(RIL) to select different

ILIMIT values

VUV = 100 VDC

VOV = 450 VDC

PI-2509-040501

Input

Voltage

D M

VUV = IUV x RLS

VOV = IOV x RLS

For RLS = 2 MΩ

VUV = 100 VDC

VOV = 450 VDC

DCMAX@100 VDC = 78%

DCMAX@375 VDC = 38%

CONTROL

RLS 2 MΩ

PI-2517-022604

Input

Voltage

D M

For RIL = 12 kΩ

ILIMIT = 69%

CONTROL

RIL

See Figures 54b, 55b

and 56b for other resistor

values (RIL) to select

different ILIMIT values.

For RIL = 25 kΩ

ILIMIT = 43%

Figure 4. Y/R/F Pkg Line Sense and Externally Set Current Limit.

Figure 5. P/G Package Line Sense.

Figure 6. P/G Package Externally Set Current Limit.

TOP242-250

4/05

TOPSwitch-GX Family Functional

Description

Like TOPSwitch, TOPSwitch-GX is an integrated switched

mode power supply chip that converts a current at the control

input to a duty cycle at the open drain output of a high voltage

power MOSFET. During normal operation the duty cycle

of the power MOSFET decreases linearly with increasing

CONTROL pin current as shown in Figure 7.

In addition to the three terminal TOPSwitch features, such as

the high voltage start-up, the cycle-by-cycle current limiting,

loop compensation circuitry, auto-restart, thermal shutdown,

the TOPSwitch-GX incorporates many additional functions that

reduce system cost, increase power supply performance and

design ﬂexibility. A patented high voltage CMOS technology

allows both the high voltage power MOSFET and all the low

voltage control circuitry to be cost effectively integrated onto

a single monolithic chip.

Three terminals, FREQUENCY, LINE-SENSE, and

EXTERNAL CURRENT LIMIT (available in Y, R or F

package) or one terminal MULTI-FUNCTION (available in P

or G package) have been added to implement some of the new

functions. These terminals can be connected to the SOURCE

pin to operate the TOPSwitch-GX in a TOPSwitch-like three

terminal mode. However, even in this three terminal mode, the

TOPSwitch-GX offers many new transparent features that do

not require any external components:

1. A fully integrated 10 ms soft-start limits peak currents

and voltages during start-up and dramatically reduces or

eliminates output overshoot in most applications.

2. DCMAX of 78% allows smaller input storage capacitor, lower

input voltage requirement and/or higher power capability.

3. Frequency reduction at light loads lowers the switching

losses and maintains good cross regulation in multiple output

supplies.

4. Higher switching frequency of 132 kHz reduces the

transformer size with no noticeable impact on EMI.

5. Frequency jittering reduces EMI.

6. Hysteretic over-temperature shutdown ensures automatic

recovery from thermal fault. Large hysteresis prevents

circuit board overheating.

7. Packages with omitted pins and lead forming provide large

drain creepage distance.

8. Tighter absolute tolerances and smaller temperature

variations on switching frequency, current limit and PWM gain.

The LINE-SENSE (L) pin is usually used for line sensing by

connecting a resistor from this pin to the rectiﬁed DC high

voltage bus to implement line overvoltage (OV), under-voltage

(UV) and line feed-forward with DCMAX reduction. In this

mode, the value of the resistor determines the OV/UV thresholds

and the DCMAX is reduced linearly starting from a line voltage

above the under-voltage threshold. See Table 2 and Figure 11.

The pin can also be used as a remote ON/OFF and a

synchronization input.

The EXTERNAL CURRENT LIMIT (X) pin is usually used

to reduce the current limit externally to a value close to the

operating peak current, by connecting the pin to SOURCE

through a resistor. This pin can also be used as a remote

ON/OFF and a synchronization input in both modes. See

Table 2 and Figure 11.

For the P or G packages the LINE-SENSE and EXTERNAL

CURRENT LIMIT pin functions are combined on one MULTI-

FUNCTION (M) pin. However, some of the functions become

mutually exclusive as shown in Table 3.

The FREQUENCY (F) pin in the Y, R or F package sets the

switching frequency to the default value of 132 kHz when

connected to SOURCE pin. A half frequency option of

66 kHz can be chosen by connecting this pin to CONTROL pin

instead. Leaving this pin open is not recommended.

PI-2633-011502

Duty Cycle (%)

IC (mA)

TOP242-5 1.6 2.0

TOP246-9 2.2 2.6

TOP250 2.4 2.7

5.2 6.0

5.8 6.6

6.5 7.3

ICD1 IB

Auto-restart

IL = 125 µA

IL < IL(DC)

IL = 190 µA

Frequency (kHz)

IC (mA)

ICD1 IB

Auto-restart

132

Note: For P and G packages IL is replaced with IM.

IL < IL(DC)

IL = 125 µA

Slope = PWM Gain

IL = 190 µA

Figure 7. Relationship of Duty Cycle and Frequency to CONTROL

Pin Current.

TOP242-250

4/05

CONTROL (C) Pin Operation

The CONTROL pin is a low impedance node that is capable

of receiving a combined supply and feedback current. During

normal operation, a shunt regulator is used to separate the

feedback signal from the supply current. CONTROL pin voltage

VC is the supply voltage for the control circuitry including the

MOSFET gate driver. An external bypass capacitor closely

connected between the CONTROL and SOURCE pins is required

to supply the instantaneous gate drive current. The total amount

of capacitance connected to this pin also sets the auto-restart

timing as well as control loop compensation.

When rectiﬁed DC high voltage is applied to the DRAIN

pin during start-up, the MOSFET is initially off, and the

CONTROL pin capacitor is charged through a switched high

voltage current source connected internally between the DRAIN

and CONTROL pins. When the CONTROL pin voltage VC

reaches approximately 5.8 V, the control circuitry is activated

and the soft-start begins. The soft-start circuit gradually

increases the duty cycle of the MOSFET from zero to the

maximum value over approximately 10 ms. If no external

feedback/supply current is fed into the CONTROL pin by the

end of the soft-start, the high voltage current source is turned

off and the CONTROL pin will start discharging in response

to the supply current drawn by the control circuitry. If the

power supply is designed properly, and no fault condition

such as open loop or shorted output exists, the feedback loop

will close, providing external CONTROL pin current, before

the CONTROL pin voltage has had a chance to discharge to

the lower threshold voltage of approximately 4.8 V (internal

supply under-voltage lockout threshold). When the externally

fed current charges the CONTROL pin to the shunt regulator

voltage of 5.8 V, current in excess of the consumption of the

chip is shunted to SOURCE through resistor RE as shown in

Figure 2. This current ﬂowing through RE controls the duty cycle

of the power MOSFET to provide closed loop regulation. The

shunt regulator has a ﬁnite low output impedance ZC that sets

the gain of the error ampliﬁer when used in a primary feedback

conﬁguration. The dynamic impedance ZC of the CONTROL

pin together with the external CONTROL pin capacitance sets

the dominant pole for the control loop.

When a fault condition such as an open loop or shorted output

prevents the ﬂow of an external current into the CONTROL

pin, the capacitor on the CONTROL pin discharges towards

4.8 V. At 4.8 V, auto-restart is activated which turns the output

MOSFET off and puts the control circuitry in a low current

standby mode. The high-voltage current source turns on and

charges the external capacitance again. A hysteretic internal

supply under-voltage comparator keeps VC within a window

of typically 4.8 V to 5.8 V by turning the high-voltage current

source on and off as shown in Figure 8. The auto-restart

circuit has a divide-by-eight counter which prevents the output

MOSFET from turning on again until eight discharge/charge

cycles have elapsed. This is accomplished by enabling the

output MOSFET only when the divide-by-eight counter reaches

full count (S7). The counter effectively limits TOPSwitch-GX

power dissipation by reducing the auto-restart duty cycle

to typically 4%. Auto-restart mode continues until output

voltage regulation is again achieved through closure of the

feedback loop.

Oscillator and Switching Frequency

The internal oscillator linearly charges and discharges an

PI-2545-082299

S1 S2 S6 S7 S1 S2 S6 S7S0 S1 S7

S0 S0 5.8 V

4.8 V

0 V

VLINE

VDRAIN

VOUT

Note: S0 through S7 are the output states of the auto-restart counter

1234

0 V

S6 S7

VUV

Figure 8. Typical Waveforms for (1) Power Up (2) Normal Operation (3) Auto-Restart (4) Power Down.

TOP242-250

4/05

internal capacitance between two voltage levels to create

a sawtooth waveform for the pulse width modulator. This

oscillator sets the pulse width modulator/current limit latch at

the beginning of each cycle.

The nominal switching frequency of 132 kHz was chosen to

minimize transformer size while keeping the fundamental EMI

frequency below 150 kHz. The FREQUENCY pin (available

only in Y, R or F package), when shorted to the CONTROL pin,

lowers the switching frequency to 66 kHz (half frequency) which

may be preferable in some cases such as noise sensitive video

applications or a high efﬁciency standby mode. Otherwise, the

FREQUENCY pin should be connected to the SOURCE pin

for the default 132 kHz.

To further reduce the EMI level, the switching frequency is

jittered (frequency modulated) by approximately ±4 kHz at

250 Hz (typical) rate as shown in Figure 9. Figure 46 shows

the typical improvement of EMI measurements with frequency

jitter.

Pulse Width Modulator and Maximum Duty Cycle

The pulse width modulator implements voltage mode control

by driving the output MOSFET with a duty cycle inversely

proportional to the current into the CONTROL pin that

is in excess of the internal supply current of the chip (see

Figure 7). The excess current is the feedback error signal that

appears across RE (see Figure 2). This signal is ﬁltered by an RC

network with a typical corner frequency of 7 kHz to reduce the

effect of switching noise in the chip supply current generated

by the MOSFET gate driver. The ﬁltered error signal is

compared with the internal oscillator sawtooth waveform to

generate the duty cycle waveform. As the control current

increases, the duty cycle decreases. A clock signal from the

oscillator sets a latch which turns on the output MOSFET. The

pulse width modulator resets the latch, turning off the output

MOSFET. Note that a minimum current must be driven into

the CONTROL pin before the duty cycle begins to change.

The maximum duty cycle, DCMAX, is set at a default maximum

value of 78% (typical). However, by connecting the LINE-

SENSE or MULTI-FUNCTION pin (depending on the

package) to the rectiﬁed DC high voltage bus through a

resistor with appropriate value, the maximum duty cycle can

be made to decrease from 78% to 38% (typical) as shown in

Figure 11 when input line voltage increases (see line feed

forward with DCMAX reduction).

Light Load Frequency Reduction

The pulse width modulator duty cycle reduces as the load at

the power supply output decreases. This reduction in duty

cycle is proportional to the current ﬂowing into the CONTROL

pin. As the CONTROL pin current increases, the duty cycle

decreases linearly towards a duty cycle of 10%. Below 10%

duty cycle, to maintain high efﬁciency at light loads, the

frequency is also reduced linearly until a minimum frequency

is reached at a duty cycle of 0% (refer to Figure 7). The

minimum frequency is typically 30 kHz and 15 kHz for

132 kHz and 66 kHz operation, respectively.

This feature allows a power supply to operate at lower

frequency at light loads thus lowering the switching losses

while maintaining good cross regulation performance and low

output ripple.

Error Ampliﬁer

The shunt regulator can also perform the function of an error

ampliﬁer in primary side feedback applications. The shunt

regulator voltage is accurately derived from a temperature-

compensated bandgap reference. The gain of the error

ampliﬁer is set by the CONTROL pin dynamic impedance.

The CONTROL pin clamps external circuit signals to the VC

voltage level. The CONTROL pin current in excess of the

supply current is separated by the shunt regulator and ﬂows

through RE as a voltage error signal.

On-Chip Current Limit with External Programmability

The cycle-by-cycle peak drain current limit circuit uses the

output MOSFET ON-resistance as a sense resistor. A current

limit comparator compares the output MOSFET on-state drain

to source voltage, VDS(ON) with a threshold voltage. High drain

current causes VDS(ON) to exceed the threshold voltage and turns

the output MOSFET off until the start of the next clock cycle.

The current limit comparator threshold voltage is temperature

compensated to minimize the variation of the current limit due

to temperature related changes in RDS(ON)

of the output MOSFET.

The default current limit of TOPSwitch-GX is preset internally.

However, with a resistor connected between EXTERNAL

CURRENT LIMIT (X) pin (Y, R or F package) or MULTI-

FUNCTION (M) pin (P or G package) and SOURCE pin,

current limit can be programmed externally to a lower level

between 30% and 100% of the default current limit. Please

refer to the graphs in the typical performance characteristics

section for the selection of the resistor value. By setting current

limit low, a larger TOPSwitch-GX than necessary for the power

PI-2550-092499

128 kHz

4 ms

Time

Switching

Frequency

VDRAIN

136 kHz

Figure 9. Switching Frequency Jitter (Idealized VDRAIN Waveforms).

TOP242-250

4/05

required can be used to take advantage of the lower RDS(ON) for

higher efﬁciency/smaller heat sinking requirements. With

a second resistor connected between the EXTERNAL

CURRENT LIMIT (X) pin (Y, R or F package) or MULTI-

FUNCTION (M) pin (P or G package) and the rectiﬁed DC

high voltage bus, the current limit is reduced with increasing

line voltage, allowing a true power limiting operation against

line variation to be implemented. When using an RCD clamp,

this power limiting technique reduces maximum clamp

voltage at high line. This allows for higher reﬂected voltage

designs as well as reducing clamp dissipation.

The leading edge blanking circuit inhibits the current limit

comparator for a short time after the output MOSFET is turned

on. The leading edge blanking time has been set so that, if a

power supply is designed properly, current spikes caused by

primary-side capacitances and secondary-side rectiﬁer reverse

recovery time should not cause premature termination of the

switching pulse.

The current limit is lower for a short period after the leading

edge blanking time as shown in Figure 52. This is due to

dynamic characteristics of the MOSFET. To avoid triggering

the current limit in normal operation, the drain current waveform

should stay within the envelope shown.

Line Under-Voltage Detection (UV)

At power up, UV keeps TOPSwitch-GX off until the input line

voltage reaches the under-voltage threshold. At power down,

UV prevents auto-restart attempts after the output goes out

of regulation. This eliminates power down glitches caused

by slow discharge of the large input storage capacitor present

in applications such as standby supplies. A single resistor

connected from the LINE-SENSE pin (Y, R or F package) or

MULTI-FUNCTION pin (P or G package) to the rectiﬁed DC

high voltage bus sets UV threshold during power up. Once the

power supply is successfully turned on, the UV threshold is

lowered to 40% of the initial UV threshold to allow extended

input voltage operating range (UV low threshold). If the UV

low threshold is reached during operation without the power

supply losing regulation, the device will turn off and stay off

until UV (high threshold) has been reached again. If the power

supply loses regulation before reaching the UV low threshold,

the device will enter auto-restart. At the end of each auto-

restart cycle (S7), the UV comparator is enabled. If the UV

high threshold is not exceeded the MOSFET will be disabled

during the next cycle (see Figure 8). The UV feature can

be disabled independent of the OV feature as shown in

Figures 19 and 23.

Line Overvoltage Shutdown (OV)

The same resistor used for UV also sets an overvoltage threshold

which, once exceeded, will force TOPSwitch-GX output into

off-state. The ratio of OV and UV thresholds is preset at 4.5

as can be seen in Figure 11. When the MOSFET is off, the

rectiﬁed DC high voltage surge capability is increased to the

voltage rating of the MOSFET (700 V), due to the absence

of the reﬂected voltage and leakage spikes on the drain. A

small amount of hysteresis is provided on the OV threshold to

prevent noise triggering. The OV feature can be disabled

independent of the UV feature as shown in Figures 18 and 32.

Line Feed-Forward with DCMAX Reduction

The same resistor used for UV and OV also implements line

voltage feed-forward, which minimizes output line ripple and

reduces power supply output sensitivity to line transients.

This feed-forward operation is illustrated in Figure 7 by the

different values of IL

(Y, R or F package) or IM (P or G package).

Note that for the same CONTROL pin current, higher line

voltage results in smaller operating duty cycle. As an added

PI-2637-060600

Oscillator

(SAW)

DMAX

Enable from

X, L or M Pin (STOP)

Time

Figure 10. Synchronization Timing Diagram.

TOP242-250

4/05

feature, the maximum duty cycle DCMAX is also reduced

from 78% (typical) at a voltage slightly higher than the UV

threshold to 30% (typical) at the OV threshold (see Figure 11).

Limiting DCMAX at higher line voltages helps prevent transformer

saturation due to large load transients in TOP248, TOP249 and

TOP250 forward converter applications. DCMAX of 38% at

high line was chosen to ensure that the power capability of the

TOPSwitch-GX is not restricted by this feature under normal

operation.

Remote ON/OFF and Synchronization

TOPSwitch-GX can be turned on or off by controlling the

current into the LINE-SENSE pin or out from the EXTERNAL

CURRENT LIMIT pin (Y, R or F package) and into or out

from the MULTI-FUNCTION pin (P or G package) (see

Figure 11). In addition, the LINE-SENSE pin has a 1 V

threshold comparator connected at its input. This voltage

threshold can also be used to perform remote ON/OFF

control. This allows easy implementation of remote

ON/OFF control of TOPSwitch-GX in several different ways.

A transistor or an optocoupler output connected between

the EXTERNAL CURRENT LIMIT or LINE-SENSE pins

(Y, R or F package) or the MULTI-FUNCTION pin (P or G

package) and the SOURCE pin implements this function with

“active-on” (Figures 22, 29 and 36) while a transistor or an

optocoupler output connected between the LINE-SENSE pin

(Y, R or F package) or the MULTI-FUNCTION (P or G package)

pin and the CONTROL pin implements the function with

“active-off” (Figures 23 and 37).

When a signal is received at the LINE-SENSE pin or the

EXTERNAL CURRENT LIMIT pin (Y, R or F package) or

the MULTI-FUNCTION pin (P or G package) to disable the

output through any of the pin functions such as OV, UV and

remote ON/OFF, TOPSwitch-GX always completes its current

switching cycle, as illustrated in Figure 10, before the output is

forced off. The internal oscillator is stopped slightly before the

end of the current cycle and stays there as long as the disable

signal exists. When the signal at the above pins changes state

from disable to enable, the internal oscillator starts the next

switching cycle. This approach allows the use of these pins

to synchronize TOPSwitch-GX to any external signal with a

frequency between its internal switching frequency and 20 kHz.

As seen above, the remote ON/OFF feature allows the

TOPSwitch-GX to be turned on and off instantly, on a cycle-

by-cycle basis, with very little delay. However, remote

ON/OFF can also be used as a standby or power switch to

turn off the TOPSwitch-GX and keep it in a very low power

consumption state for indeﬁnitely long periods. If the

TOPSwitch-GX is held in remote off state for long enough

time to allow the CONTROL pin to discharge to the internal

supply under-voltage threshold of 4.8 V (approximately 32 ms

for a 47 µF CONTROL pin capacitance), the CONTROL pin

goes into the hysteretic mode of regulation. In this mode, the

CONTROL pin goes through alternate charge and discharge

cycles between 4.8 V and 5.8 V (see CONTROL pin operation

section above) and runs entirely off the high voltage DC input,

but with very low power consumption (160 mW typical at

230 VAC with M or X pins open). When the TOPSwitch-GX

is remotely turned on after entering this mode, it will initiate

a normal start-up sequence with soft-start the next time the

CONTROL pin reaches 5.8 V. In the worst case, the delay from

remote on to start-up can be equal to the full discharge/charge

cycle time of the CONTROL pin, which is approximately

125 ms for a 47 µF CONTROL pin capacitor. This

reduced consumption remote off mode can eliminate

expensive and unreliable in-line mechanical switches. It also

allows for microprocessor controlled turn-on and turn-off

sequences that may be required in certain applications such as

inkjet and laser printers.

Soft-Start

Two on-chip soft-start functions are activated at start-up with a

duration of 10 ms (typical). Maximum duty cycle starts from

0% and linearly increases to the default maximum of 78% at

the end of the 10 ms duration and the current limit starts from

about 85% and linearly increases to 100% at the end of the

10 ms duration. In addition to start-up, soft-start is also

activated at each restart attempt during auto-restart and when

restarting after being in hysteretic regulation of CONTROL

pin voltage (VC), due to remote OFF or thermal shutdown

conditions. This effectively minimizes current and voltage

stresses on the output MOSFET, the clamp circuit and the

output rectiﬁer during start-up. This feature also helps

minimize output overshoot and prevents saturation of the

transformer during start-up.

Shutdown/Auto-Restart

To minimize TOPSwitch-GX power dissipation under fault

conditions, the shutdown/auto-restart circuit turns the power

supply on and off at an auto-restart duty cycle of typically 4%

if an out of regulation condition persists. Loss of regulation

interrupts the external current into the CONTROL pin. VC

regulation changes from shunt mode to the hysteretic auto-

restart mode as described in CONTROL pin operation section.

When the fault condition is removed, the power supply output

becomes regulated, VC regulation returns to shunt mode, and

normal operation of the power supply resumes.

Hysteretic Over-Temperature Protection

Temperature protection is provided by a precision analog

circuit that turns the output MOSFET off when the junction

temperature exceeds the thermal shutdown temperature

(140 °C typical). When the junction temperature cools to

below the hysteretic temperature, normal operation resumes

providing automatic recovery. A large hysteresis of 70 °C

(typical) is provided to prevent overheating of the PC board due

to a continuous fault condition. VC is regulated in hysteretic mode

and a 4.8 V to 5.8 V (typical) sawtooth waveform is present on

the CONTROL pin while in thermal shutdown.

TOP242-250

4/05

Table 2. Typical LINE-SENSE and EXTERNAL CURRENT LIMIT Pin Conﬁgurations.

Bandgap Reference

All critical TOPSwitch-GX internal voltages are derived from

a temperature-compensated bandgap reference. This reference

is also used to generate a temperature-compensated current

reference, which is trimmed to accurately set the switching

frequency, MOSFET gate drive current, current limit, and the

line OV/UV thresholds. TOPSwitch-GX has improved circuitry

to maintain all of the above critical parameters within very tight

absolute and temperature tolerances.

High-Voltage Bias Current Source

This current source biases TOPSwitch-GX from the DRAIN

pin and charges the CONTROL pin external capacitance

during start-up or hysteretic operation. Hysteretic operation

occurs during auto-restart, remote OFF and over-temperature

shutdown. In this mode of operation, the current source

is switched on and off with an effective duty cycle of

approximately 35%. This duty cycle is determined by the

ratio of CONTROL pin charge (IC) and discharge currents

(ICD1 and ICD2). This current source is turned off during normal

operation when the output MOSFET is switching. The effect of

the current source switching will be seen on the DRAIN voltage

waveform as small disturbances and is normal.

Using Feature Pins

FREQUENCY (F) Pin Operation

The FREQUENCY pin is a digital input pin available in the

Y, R or F package only. Shorting the FREQUENCY pin to

SOURCE pin selects the nominal switching frequency of

132 kHz (Figure 13), which is suited for most applications.

For other cases that may beneﬁt from lower switching

frequency such as noise sensitive video applications, a

66 kHz switching frequency (half frequency) can be selected by

shorting the FREQUENCY pin to the CONTROL pin

(Figure 14). In addition, an example circuit shown in Figure 15

may be used to lower the switching frequency from 132 kHz in

normal operation to 66 kHz in standby mode for very low

standby power consumption.

LINE-SENSE (L) Pin Operation (Y, R and F Packages)

When current is fed into the LINE-SENSE pin, it works as

a voltage source of approximately 2.6 V up to a maximum

current of +400 µA (typical). At +400 µA, this pin turns into

a constant current sink. Refer to Figure 12a. In addition, a

comparator with a threshold of 1 V is connected at the pin and

is used to detect when the pin is shorted to the SOURCE pin.

There are a total of four functions available through the use of

the LINE-SENSE pin: OV, UV, line feed-forward with DCMAX

reduction, and remote ON/OFF. Connecting the LINE-SENSE

pin to the SOURCE pin disables all four functions. The LINE-

SENSE pin is typically used for line sensing by connecting a

resistor from this pin to the rectiﬁed DC high voltage bus to

implement OV, UV and DCMAX reduction with line voltage. In

this mode, the value of the resistor determines the line OV/UV

thresholds, and the DCMAX is reduced linearly with rectiﬁed DC

high voltage starting from just above the UV threshold. The pin

can also be used as a remote ON/OFF and a synchronization

input. Refer to Table 2 for possible combinations of the functions

with example circuits shown in Figure 16 through Figure 40. A

description of speciﬁc functions in terms of the LINE-SENSE

pin I/V characteristic is shown in Figure 11 (right hand side).

The horizontal axis represents LINE-SENSE pin current with

positive polarity indicating currents ﬂowing into the pin. The

meaning of the vertical axes varies with functions. For those

that control the ON/OFF states of the output such as UV, OV

and remote ON/OFF, the vertical axis represents the enable/

disable states of the output. UV triggers at IUV (+50 µA typical

with 30 µA hysteresis) and OV triggers at IOV (+225 µA

typical with 8 µA hysteresis). Between the UV and OV

thresholds, the output is enabled. For line feed-forward with

LINE-SENSE AND EXTERNAL CURRENT LIMIT PIN TABLE*

Figure Number 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Three Terminal Operation ✓

Under-Voltage ✓ ✓ ✓ ✓ ✓

Overvoltage ✓ ✓ ✓ ✓ ✓

Line Feed-Forward (DCMAX)✓ ✓ ✓ ✓

Overload Power Limiting ✓

External Current Limit ✓ ✓ ✓ ✓ ✓ ✓

Remote ON/OFF ✓ ✓ ✓ ✓ ✓ ✓ ✓

*This table is only a partial list of many LINE-SENSE and EXTERNAL CURRENT LIMIT pin conﬁgurations that are possible.

▼

TOP242-250

4/05

DCMAX reduction, the vertical axis represents the magnitude of

the DCMAX. Line feed-forward with DCMAX reduction lowers

maximum duty cycle from 78% at IL(DC) (+60 µA typical) to

38% at IOV (+225 µA).

EXTERNAL CURRENT LIMIT (X) Pin Operation

(Y, R and F Packages)

When current is drawn out of the EXTERNAL CURRENT

LIMIT pin, it works as a voltage source of approximately

1.3 V up to a maximum current of -240 µA (typical). At

-240 µA, it turns into a constant current source (refer to

Figure 12a).

There are two functions available through the use of the

EXTERNAL CURRENT LIMIT pin: external current limit

and remote ON/OFF. Connecting the EXTERNAL CURRENT

LIMIT pin to the SOURCE pin disables the two functions. In

high efﬁciency applications, this pin can be used to reduce the

current limit externally to a value close to the operating peak

current by connecting the pin to the SOURCE pin through

a resistor. The pin can also be used for remote ON/OFF.

Table 2 shows several possible combinations using this pin. See

Figure 11 for a description of the functions where the horizontal

axis (left hand side) represents the EXTERNAL CURRENT

LIMIT pin current. The meaning of the vertical axes varies

with function. For those that control the ON/OFF states of the

output such as remote ON/OFF, the vertical axis represents the

enable/disable states of the output. For external current limit,

the vertical axis represents the magnitude of the ILIMIT. Please

see graphs in the Typical Performance Characteristics section

for the current limit programming range and the selection of

appropriate resistor value.

MULTI-FUNCTION (M) Pin Operation (P and G

Packages)

The LINE-SENSE and EXTERNAL CURRENT LIMIT pin

functions are combined to a single MULTI-FUNCTION pin

for P and G packages. The comparator with a 1 V threshold

at the LINE-SENSE pin is removed in this case as shown in

Figure 2b. All of the other functions are kept intact. However,

since some of the functions require opposite polarity of input

current (MULTI-FUNCTION pin), they are mutually exclusive.

For example, line sensing features cannot be used simultaneously

with external current limit setting. When current is fed into

the MULTI-FUNCTION pin, it works as a voltage source of

approximately 2.6 V up to a maximum current of +400 µA

(typical). At +400 µA, this pin turns into a constant current

sink. When current is drawn out of the MULTI-FUNCTION

pin, it works as a voltage source of approximately 1.3 V up to

a maximum current of -240 µA (typical). At -240 µA, it turns

into a constant current source. Refer to Figure 12b.

There are a total of ﬁve functions available through the use

of the MULTI-FUNCTION pin: OV, UV, line feed-forward

with DCMAX reduction, external current limit and remote

ON/OFF. A short circuit between the MULTI-FUNCTION

pin and SOURCE pin disables all ﬁve functions and forces

TOPSwitch-GX to operate in a simple three terminal mode

like TOPSwitch-II. The MULTI-FUNCTION pin is typically

used for line sensing by connecting a resistor from this pin to

the rectiﬁed DC high voltage bus to implement OV, UV and

DCMAX reduction with line voltage. In this mode, the value

of the resistor determines the line OV/UV thresholds, and the

DCMAX is reduced linearly with increasing rectiﬁed DC high

voltage starting from just above the UV threshold. External

current limit programming is implemented by connecting the

MULTI-FUNCTION pin to the SOURCE pin through a resistor.

However, this function is not necessary in most applications

since the internal current limit of the P and G package devices

has been reduced, compared to the Y, R and F package

devices, to match the thermal dissipation capability of the P

and G packages. It is therefore recommended that the MULTI-

FUNCTION pin is used for line sensing as described above and

not for external current limit reduction. The same pin can also

Table 3. Typcial MULTI-FUNCTION Pin Conﬁgurations.

MULTI-FUNCTION PIN TABLE*

Figure Number 30 31 32 33 34 35 36 37 38 39 40

Three Terminal Operation ✓

Under-Voltage ✓ ✓ ✓

Overvoltage ✓ ✓ ✓

Line Feed-Forward (DCMAX)✓ ✓

Overload Power Limiting ✓

External Current Limit ✓ ✓ ✓ ✓

Remote ON/OFF ✓✓✓✓✓

*This table is only a partial list of many MULTI-FUNCTION pin conﬁgurations that are possible.

▼

TOP242-250

4/05

be used as a remote ON/OFF and a synchronization input in

both modes. Please refer to Table 3 for possible combinations

of the functions with example circuits shown in Figure 30

through Figure 40. A description of speciﬁc functions in terms

of the MULTI-FUNCTION pin I/V characteristic is shown in

Figure 11. The horizontal axis represents MULTI-FUNCTION

pin current with positive polarity indicating currents ﬂowing into

the pin. The meaning of the vertical axes varies with functions.

For those that control the ON/OFF states of the output such

as UV, OV and remote ON/OFF, the vertical axis represents

the enable/disable states of the output. UV triggers at IUV

(+50 µA typical) and OV triggers at IOV (+225 µA typical with

30 µA hysteresis). Between the UV and OV thresholds, the

output is enabled. For external current limit and line feed-

forward with DCMAX reduction, the vertical axis represents the

magnitude of the ILIMIT and DCMAX. Line feed-forward with

DCMAX reduction lowers maximum duty cycle from 78% at IM(DC)

(+60 µA typical) to 38% at IOV (+225 µA). External current

limit is available only with negative MULTI-FUNCTION

pin current. Please see graphs in the Typical Performance

Characteristics section for the current limit programming

range and the selection of appropriate resistor value.

-250 -200 -150 -100 -50 0 50 100 150 200 250 300 350 400

PI-2636-010802

Output

MOSFET

Switching

(Enabled)

(Disabled)

ILIMIT (Default)

DCMAX (78.5%)

Current

Limit

M Pin

L PinX Pin

Maximum

Duty Cycle

VBG

-22 µA

-27 µAVBG + VTP

IUV

IREM(N) IOV

Pin Voltage

Note: This figure provides idealized functional characteristics with typical performance values. Please refer to the parametric

table and typical performance characteristics sections of the data sheet for measured data.

X and L Pins (Y, R or F Package) and M Pin (P or G Package) Current (µA)

Disabled when supply

output goes out of

regulation

Figure 11. MULTI-FUNCTION (P or G package), LINSE-SENSE, and EXTERNAL CURRENT LIMIT (Y, R or F package) Pin Characteristics.

TOP242-250

4/05

VBG + VT

1 V

VBG

240 µA

400 µA

CONTROL (C)

Y, R and F Package

(Voltage Sense)

(Positive Current Sense - Under-Voltage,

Overvoltage, ON/OFF Maximum Duty

Cycle Reduction)

(Negative Current Sense - ON/OFF,

Current Limit Adjustment)

PI-2634-022604

TOPSwitch-GX

LINE-SENSE (L)

EXTERNAL CURRENT LIMIT (X)

VBG + VT

VBG

240 µA

400 µA

CONTROL (C)

MULTI-FUNCTION (M)

(Positive Current Sense - Under-Voltage,

Overvoltage, Maximum Duty

Cycle Reduction)

(Negative Current Sense - ON/OFF,

Current Limit Adjustment)

PI-2548-022604

TOPSwitch-GX

P and G Package

Figure 12a. LINE-SENSE (L), and EXTERNAL CURRENT LIMIT (X) Pin Input Simpliﬁed Schematic.

Figure 12b. MULTI-FUNCTION (M) Pin Input Simpliﬁed Schematic.

TOP242-250

4/05

Typical Uses of FREQUENCY (F) PIN

PI-2654-071700

Input

Voltage

CONTROL

PI-2655-071700

Input

Voltage

CONTROL

PI-2656-040501

Input

Voltage

STANDBY

QS can be an optocoupler output.

CONTROL

20 kΩ

RHF 1 nF

47 kΩ

Figure 13. Full Frequency Operation (132 kHz). Figure 14. Half Frequency Operation (66 kHz).

Figure 15. Half Frequency Standby Mode (For High Standby

Efﬁciency).

TOP242-250

4/05

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) P ins

X F

PI-2617-050100

Input

Voltage

C S D

CONTROL

C L X S F D

PI-2618-081403

Input

Voltage

CONTROL

2 MΩRLS

VUV = IUV x RLS

VOV = IOV x RLS

For RLS = 2 MΩ

VUV = 100 VDC

VOV = 450 VDC

DCMAX@100 VDC = 78%

DCMAX@375 VDC = 38%

PI-2510-040501

Input

Voltage

D M

VUV = RLS x IUV

For Value Shown

VUV = 100 VDC

RLS

6.2 V

2 MΩ

22 kΩ

CONTROL

PI-2620-040501

Input

Voltage

CONTROL

2 MΩ

30 kΩ

RLS

1N4148

VOV = IOV x RLS

For Values Shown

VOV = 450 VDC

PI-2623-092303

Input

Voltage

RIL

For RIL = 12 kΩ

ILIMIT = 69%

See Figure 54b for

other resistor values

(RIL)

For RIL = 25 kΩ

ILIMIT = 43%

CONTROL

PI-2624-040501

Input

Voltage

2.5 MΩ

RLS

6 kΩ

RIL

100% @ 100 VDC

63% @ 300 VDC

ILIMIT =

CONTROL

Figure 16. Three Terminal Operation (LINE-SENSE and

EXTERNAL CURRENT LIMIT Features Disabled.

FREQUENCY Pin Tied to SOURCE or CONTROL Pin).

Figure 17. Line-Sensing for Under-Voltage, Overvoltage and Line

Feed-Forward.

Figure 20. Externally Set Current Limit. Figure 21. Current Limit Reduction with Line Voltage.

Figure 18. Line-Sensing for Under-Voltage Only (Overvoltage

Disabled).

Figure 19. Linse-Sensing for Overvoltage Only (Under-Voltage

Disabled). Maximum Duty Cycle Reduced at Low Line

and Further Reduction with Increasing Line Voltage.

TOP242-250

4/05

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins (cont.)

PI-2625-040501

Input

Voltage

ON/OFF

47 KΩ

QR can be an optocoupler

output or can be replaced by

a manual switch.

CONTROL

PI-2621-040501

Input

Voltage

CONTROL

47 kΩ

RMC

45 kΩ

QR can be an

optocoupler output or

can be replaced

by a manual switch.

ON/OFF

47 kΩ

PI-2626-040501

Input

Voltage

RIL QR

12 kΩ

For RIL =

ILIMIT = 69%

25 kΩ

For RIL =

ILIMIT = 43%

QR can be an optocoupler

output or can be replaced

by a manual switch.

CONTROL

PI-2627-040501

Input

Voltage

CONTROL

47 kΩ

RMC

45 kΩ

QR can be an

optocoupler output

or can be replaced

by a manual switch.

ON/OFF

RIL

PI-2622-040501

Input

Voltage

CONTROL

47 kΩ

2 MΩ

RLS

ON/OFF

For RLS = 2 MΩ

VUV = 100 VDC

VOV = 450 VDC

QR can be an optocoupler

output or can be replaced

by a manual switch.

ON/OFF

47 kΩ

PI-2628-040501

Input

Voltage

CONTROL

RIL

RLS

2 MΩ

VUV = IUV x RLS

VOV = IOV x RLS

DCMAX@100 VDC = 78%

DCMAX@375 VDC = 38%

12 kΩ

For RIL =

ILIMIT = 69%

QR can be an optocoupler

output or can be replaced

by a manual switch.

Figure 22. Active-on (Fail Safe) Remove ON/OFF. Figure 23. Active-off Remote ON/OFF. Maximum Duty Cycle

Reduced.

Figure 24. Active-on Remote ON/OFF with Externally Set Current

Limit.

Figure 25. Active-off Remote ON/OFF with Externally Set Current

Limit.

Figure 26. Active-off Remote ON/OFF with LINE-SENSE. Figure 27. Active-on Remote ON/OFF with LINE-SENSE and

EXTERNAL CURRENT LIMIT.

TOP242-250

4/05

PI-2629-092203

Input

Voltage

CONTROL

RIL

RLS

12 kΩ

2 MΩ

VUV = IUV x RLS

VOV = IOV x RLS

For RLS = 2 MΩ

DCMAX@100 VDC = 78%

DCMAX@375 VDC = 38%

For RIL = 12 kΩ

ILIMIT = 69%

See Figure 54b for

other resistor values

(RIL) to select different

ILIMIT values

VUV = 100 VDC

VOV = 450 VDC

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins (cont.)

PI-2640-040501

Input

Voltage

CONTROL

ON/OFF

47 kΩ

QR can be an optocoupler

output or can be replaced by

a manual switch.

300 kΩ

Typical Uses of MULTI-FUNCTION (M) Pin

PI-2508-081199

Input

Voltage

CONTROL

D S

C D S

S S M

PI-2509-040501

Input

Voltage

D M

VUV = IUV x RLS

VOV = IOV x RLS

For RLS = 2 MΩ

VUV = 100 VDC

VOV = 450 VDC

DCMAX@100 VDC = 78%

DCMAX@375 VDC = 38%

CONTROL

RLS 2 MΩ

PI-2510-040501

Input

Voltage

D M

VUV = RLS x IUV

For Value Shown

VUV = 100 VDC

RLS

6.2 V

2 MΩ

22 kΩ

CONTROL

PI-2516-040501

Input

Voltage

D M

VOV = IOV x RLS

For Values Shown

VOV = 450 VDC

CONTROL

RLS

1N4148

2 MΩ

30 kΩ

Figure 30. Three Terminal Operation (MULIT-FUNCTION Features

Disabled).

Figure 31. Line-Sensing for Undervoltage, Over-Voltage and Line

Feed-Forward.

Figure 32. Line-Sensing for Under-Voltage Only (Overvoltage

Disabled).

Figure 33. Line-Sensing for Overvoltage Only (Under-Voltage

Disabled). Maximum Duty Cycle Reduced at Low Line

and Further Reduction with Increasing Line Voltage.

Figure 28. Line-Sensing and Externally Set Current Limit. Figure 29. Active-on Remote ON/OFF.

TOP242-250

4/05

Typical Uses of MULTI-FUNCTION (M) Pin (cont.)

Figure 34. Externally Set Current Limit (Not Normally Required-See

M Pin Operation Description).

PI-2517-022604

Input

Voltage

D M

For RIL = 12 kΩ

ILIMIT = 69%

CONTROL

RIL

See Figures 54b, 55b

and 56b for other resistor

values (RIL) to select

different ILIMIT values.

For RIL = 25 kΩ

ILIMIT = 43%

PI-2518-040501

Input

Voltage

D M

CONTROL

RIL

RLS 2.5 MΩ

6 kΩ

100% @ 100 VDC

63% @ 300 VDC

ILIMIT =

Figure 35. Current Limit Reduction with Line Voltage (Not Normally

Required-See M Pin Operation Description).

Figure 36. Active-on (Fail Safe) Remote ON/OFF.

PI-2519-040501

Input

Voltage

ON/OFF

CONTROL

QR can be an optocoupler

output or can be replaced

by a manual switch.

47 kΩ

PI-2522-040501

Input

Voltage

RMC

45 kΩ

CONTROL

QR can be an optocoupler

output or can be replaced

by a manual switch.

ON/OFF

47 kΩ

Figure 37. Active-off Remote ON/OFF. Maximum Duty Cycle

Reduced.

TOP242-250

4/05

Typical Uses of MULTI-FUNCTION (M) Pin (cont.)

PI-2520-040501

Input

Voltage

RIL M

CONTROL

12 kΩ

For RIL =

ILIMIT = 69%

QR can be an optocoupler

output or can be replaced

by a manual switch.

ON/OFF

47 kΩ

25 kΩ

For RIL =

ILIMIT = 43%

PI-2521-040501

Input

Voltage

RIL

RMC 24 kΩ

12 kΩ

CONTROL

2RIL

RMC =

QR can be an optocoupler

output or can be replaced

by a manual switch.

ON/OFF

47 kΩ

PI-2523-040501

Input

Voltage

RLS

For RLS = 2 MΩ

VUV = 100 VDC

VOV = 450 VDC

CONTROL

2 MΩ

QR can be an optocoupler

output or can be replaced

by a manual switch.

ON/OFF

47 kΩ

Figure 38. Active-on Remote ON/OFF with Externally Set Current

Limit (See M Pin Operation Description).

Figure 39. Active-off Remote ON/OFF with Externally Set Current

Limit (See M Pin Operation Description).

Figure 40. Active-off Remote ON/OFF with LINE-SENSE.

TOP242-250

4/05

Figure 41. 30 W Power Supply using External Current Limit Programming and Line Sensing for UV and OV.

12 V @

2.5 A

1N4148

47 µF

10 V

LTV817A

VR2

1N5240C

10 V, 2%

150 Ω

R15

150 Ω

C14

1 nF

UF4005

68 kΩ

2 W

4.7 nF

1 kV

CY1

2.2 nF

TOP244Y

D L

S X F

150 Ω

68 µF

400 V

0.1 µF

MBR1060

C10

560 µF

35 V

C12

220 µF

35 V

C11

560 µF

35 V

RTN

6.8 Ω

4.7 MΩ

1/2 W

2 MΩ

1/2 W

9.09 kΩ

PI-2657-081204

3.3 µH

BR1

600 V

3.15 A

20 mH

CX1

100 nF

250 VAC CONTROL

CONTROL

TOPSwitch-GX

PERFORMANCE SUMMARY

Output Power: 30 W

Regulation: ± 4%

Efficiency: ≥ 79%

Ripple: ≤ 50 mV pk-pk

Application Examples

A High Efﬁciency, 30 W, Universal Input Power Supply

The circuit shown in Figure 41 takes advantage of several of

the TOPSwitch-GX features to reduce system cost and power

supply size and to improve efﬁciency. This design delivers

30 W at 12 V, from an 85 VAC to 265 VAC input, at an ambient

of 50 °C, in an open frame conﬁguration. A nominal efﬁciency

of 80% at full load is achieved using TOP244Y.

The current limit is externally set by resistors R1 and R2 to a

value just above the low line operating peak DRAIN current

of approximately 70% of the default current limit. This

allows use of a smaller transformer core size and/or higher

transformer primary inductance for a given output power,

reducing TOPSwitch-GX power dissipation, while at the same

time avoiding transformer core saturation during startup and

output transient conditions. The resistors R1 & R2 provide a

signal that reduces the current limit with increasing line voltage,

which in turn limits the maximum overload power at high input

line voltage. This function in combination with the built-in

soft-start feature of TOPSwitch-GX, allows the use of a low cost

RCD clamp (R3, C3 and D1) with a higher reﬂected voltage,

by safely limiting the TOPSwitch-GX drain voltage, with

adequate margin under worst case conditions. Resistor R4

provides line sensing, setting UV at 100 VDC and OV at

450 VDC. The extended maximum duty cycle feature of

TOPSwitch-GX (guaranteed minimum value of 75% vs. 64%

for TOPSwitch-II) allows the use of a smaller input capacitor

(C1). The extended maximum duty cycle and the higher

reﬂected voltage possible with the RCD clamp also permit

the use of a higher primary to secondary turns ratio for T1,

which reduces the peak reverse voltage experienced by the

secondary rectiﬁer D8. As a result a 60 V Schottky rectiﬁer

can be used for up to 15 V outputs, which greatly improves

power supply efﬁciency. The frequency reduction feature of the

TOPSwitch-GX eliminates the need for any dummy loading

for regulation at no load and reduces the no-load/standby

consumption of the power supply. Frequency jitter provides

improved margin for conducted EMI, meeting the CISPR 22

(FCC B) speciﬁcation.

Output regulation is achieved by using a simple Zener sense

circuit for low cost. The output voltage is determined by the

Zener diode (VR2) voltage and the voltage drops across the

optocoupler (U2) LED and resistor R6. Resistor R8 provides

bias current to Zener VR2 for typical regulation of ±5% at

the 12 V output level, over line and load and component

variations.

A High Efﬁciency, Enclosed, 70 W, Universal Adapter Supply

The circuit shown in Figure 42 takes advantage of several of the

TOPSwitch-GX features to reduce cost, power supply size and

TOP242-250

4/05

increase efﬁciency. This design delivers 70 W at 19 V, from an

85 VAC to 265 VAC input, at an ambient of 40 °C, in a small

sealed adapter case (4” x 2.15” x 1”). Full load efﬁciency is

85% at 85 VAC rising to 90% at 230 VAC input.

Due to the thermal environment of a sealed adapter, a TOP249Y

is used to minimize device dissipation. Resistors R9 and R10

externally program the current limit level to just above the

operating peak DRAIN current at full load and low line. This

allows the use of a smaller transformer core size without

saturation during startup or output load transients. Resistors

R9 and R10 also reduce the current limit with increasing line

voltage, limiting the maximum overload power at high input

line voltage, removing the need for any protection circuitry on

the secondary. Resistor R11 implements an under-voltage and

overvoltage sense as well as providing line feed-forward for

reduced output line frequency ripple. With resistor R11 set at

2 MΩ, the power supply does not start operating until the DC

rail voltage reaches 100 VDC. On removal of the AC input,

the UV sense prevents the output glitching as C1 discharges,

turning off the TOPSwitch-GX when the output regulation is

lost or when the input voltage falls to below 40 V, whichever

occurs ﬁrst. This same value of R11 sets the OV threshold to

450 V. If exceeded, for example during a line surge,

TOPSwitch-GX stops switching for the duration of the surge,

extending the high voltage withstand to 700 V without device

damage. Capacitor C11 has been added in parallel with VR1 to

reduce Zener clamp dissipation. With a switching frequency of

132 kHz, a PQ26/20 core can be used to provide 70 W. To

maximize efﬁciency, by reducing winding losses, two output

windings are used each with their own dual 100 V Schottky

rectiﬁer (D2 and D3). The frequency reduction feature of the

TOPSwitch-GX eliminates any dummy loading to maintain

regulation at no load and reduces the no-load consumption of

the power supply to only 520 mW at 230 VAC input. Frequency

jittering provides conducted EMI meeting the CISPR 22

(FCC B) / EN55022B speciﬁcation, using simple ﬁlter components

(C7, L2, L3 and C6), even with the output earth grounded.

To regulate the output, an optocoupler (U2) is used with a

secondary reference sensing the output voltage via a resistor

divider (U3, R4, R5, R6). Diode D4 and C15 ﬁlter and smooth

the output of the bias winding. Capacitor C15 (1 µF) prevents

the bias voltage from falling during zero to full load transients.

Resistor R8 provides ﬁltering of leakage inductance spikes,

keeping the bias voltage constant even at high output loads.

Resistor R7, C9 and C10 together with C5 and R3 provide

loop compensation.

Due to the large primary currents, all the small signal control

components are connected to a separate source node that is

Kelvin connected to the SOURCE pin of the TOPSwitch-GX.

For improved common-mode surge immunity, the bias winding

common returns directly to the DC bulk capacitor (C1).

19 V

@ 3.6 A

TOP249Y

TL431

PC817A

D L

S X F

RTN

820 µH

0.1 µF

3.15 A

85-265 VAC

BR1

RS805

8A 600 V

75 µH

t°

C13

0.33 µF

400 V

C12

0.022 µF

400 V

C11

0.01 µF

400 V

RT1

10 Ω

1.7 A

PI-2691-042203

All resistors 1/8 W 5% unless otherwise stated.

CONTROL

TOPSwitch-GX

150 µF

400 V

PERFORMANCE SUMMARY

Output Power: 70 W

Regulation: ± 4%

Efficiency: ≥ 84%

Ripple: ≤ 120 mV pk-pk

No Load Consumption: < 0.52 W @ 230 VAC

47 µF

16 V

820 µF

25 V L1

200 µH

820 µF

25 V

C14

0.1 µF

50 V

820 µF

25 V

C10

0.1 µF

50 V

4.7 nF 50 V

0.1 µF

50 V

VR1

P6KE-

200

MBR20100

C7 2.2 nF

Y1 Safety

MBR20100

1N4148

R11

2 MΩ

1/2 W

13 MΩ

4.7 Ω

270 Ω

1 kΩR5

562 Ω

31.6 kΩ

56 kΩ

R10

20.5 kΩ

6.8 Ω

4.75 kΩ

C15

1 µF

50 V

UF4006

Figure 42. 70 W Power Supply using Current Limit Reduction with Line and Line Sensing for UV and OV.

TOP242-250

4/05

A High Efﬁciency, 250 W, 250-380 VDC Input Power Supply

The circuit shown in Figure 43 delivers 250 W (48 V @

5.2 A) at 84% efﬁciency using a TOP249 from a 250 VDC to

380 VDC input. DC input is shown, as typically at this power

level a p.f.c. boost stage would preceed this supply, providing the

DC input (C1 is included to provide local decoupling). Flyback

topology is still usable at this power level due to the high output

voltage, keeping the secondary peak currents low enough so

that the output diode and capacitors are reasonably sized.

In this example, the TOP249 is at the upper limit of its power

capability and the current limit is set to the internal maximum

by connecting the X pin to SOURCE. However, line sensing

is implemented by connecting a 2 MΩ resistor from the L pin

to the DC rail. If the DC input rail rises above 450 VDC, then

TOPSwitch-GX will stop switching until the voltage returns to

normal, preventing device damage.

Due to the high primary current, a low leakage inductance

transformer is essential. Therefore, a sandwich winding with

a copper foil secondary was used. Even with this technique,

the leakage inductance energy is beyond the power capability

of a simple Zener clamp. Therefore, R2, R3 and C6 are added

in parallel to VR1. These have been sized such that during

normal operation, very little power is dissipated by VR1,

the leakage energy instead being dissipated by R2 and R3.

However, VR1 is essential to limit the peak drain voltage

during start-up and/or overload conditions to below the 700 V

rating of the TOPSwitch-GX MOSFET.

The secondary is rectifed and smoothed by D2 and C9, C10 and

C11. Three capacitors are used to meet the secondary ripple

current requirement. Inductor L2 and C12 provide switching

noise ﬁltering.

A simple Zener sensing chain regulates the output voltage.

The sum of the voltage drop of VR2, VR3 and VR4 plus the

LED drop of U2 gives the desired output voltage. Resistor R6

limits LED current and sets overall control loop DC gain.

Diode D4 and C14 provide secondary soft-ﬁnish, feeding

current into the CONTROL pin prior to output regulation and

thus ensuring that the output voltage reaches regulation at start-

up under low line, full load conditions. Resistor R9 provides a

discharge path for C14. Capacitor C13 and R8 provide control

loop compensation and are required due to the gain associated

with such a high output voltage.

Sufﬁcient heat sinking is required to keep the TOPSwitch-GX

device below 110 °C when operating under full load, low line

and maximum ambient temperature. Airﬂow may also be

required if a large heatsink area is not acceptable.

48 V@

5.2 A

+250-380

VDC

0 V

S X F

RTN

PI-2692-081204

All resistor 1/8 W 5% unless

otherwise stated.

CONTROL

TOPSwitch-GX

22 µF

400 V

0.1 µF

50 V

6.8 Ω

100 Ω

56 Ω

10 kΩ

47 µF

10 V

4.7 nF

1 kV

C13

150 nF

63 V

1 µF

50 V

C14

22 µF

63 V

560 µF

63 V

C10

560 µF

63 V

C11

560 µF

63 V

C12

68 µF

63 V

2.2 nF Y1

3 µH 8A

MUR1640CT

1N4148 U2

LTV817A

BYV26C

2 MΩ

1/2 W

68 kΩ

2 W

68 kΩ

2 W

VR1

P6KE200

VR2 22 V

BZX79B22

VR3 12 V

BZX79B12

VR4 12 V

BZX79B12

CONTROL

1N4148

PERFORMANCE SUMMARY

Output Power: 250 W

Line Regulation: ± 1%

Load Regulation: ± 5%

Efficiency: ≥ 85%

Ripple: < 100 mV pk-pk

No Load Consumption: ≤ 1.4 W (300 VDC)

TOP249Y

Figure 43. 250 W, 48 V Power Supply using TOP249.

TOP242-250

4/05

Multiple Output, 60 W, 185-265 VAC Input Power Supply

Figure 44 shows a multiple output supply typical for high end

set-top boxes or cable decoders containing high capacity hard

disks for recording. The supply delivers an output power of

45 W continuous/60 W peak (thermally limited) from an input

voltage of 185 VAC to 265 VAC. Efﬁciency at 45 W,

185 VAC is ≥ 75%.

The 3.3 V and 5 V outputs are regulated to ±5% without

the need for secondary linear regulators. DC stacking (the

secondary winding reference for the other output voltages is

connected to the cathode of D10 rather than the anode) is used

to minimize the voltage error for the higher voltage outputs.

Due to the high ambient operating temperature requirement

typical of a set-top box (60 °C), the TOP246Y is used to

reduce conduction losses and minimize heatsink size. Resistor

R2 sets the device current limit to 80% of typical to limit

overload power. The line sense resistor (R1) protects the

TOPSwitch-GX from line surges and transients by sensing when

the DC rail voltage rises to above 450 V. In this condition the

TOPSwitch-GX stops switching, extending the input voltage

withstand to 496 VAC, which is ideal for countries with

poor power quality. A thermistor (RT1) is used to prevent

premature failure of the fuse by limiting the inrush current (due

to the relatively large size of C2). An optional MOV (RV1)

extends the differential surge protection to 6 kV from 4 kV.

Leakage inductance clamping is provided by VR1, R5 and C5,

keeping the DRAIN voltage below 700 V under all conditions.

Resistor R5 and capacitor C5 are selected such that VR1

dissipates very little power except during overload conditions.

The frequency jittering feature of TOPSwitch-GX allows the

circuit shown to meet CISPR22B with simple EMI ﬁltering

(C1, L1 and C6) and the output grounded.

The secondaries are rectiﬁed and smoothed by D7 to D11, C7,

C9, C11, C13, C14, C16 and C17. Diode D11 for the 3.3 V

output is a Schottky diode to maximize efﬁciency. Diode D10

for the 5 V output is a PN type to center the 5 V output at 5 V.

The 3.3 V and 5 V output require two capacitors in parallel to

meet the ripple current requirement. Switching noise ﬁltering

is provided by L2 to L5 and C8, C10, C12, C15 and C18.

Resistor R6 prevents peak charging of the lightly loaded 30 V

output. The outputs are regulated using a secondary reference

(U3). Both the 3.3 V and 5 V outputs are sensed via R11

and R10. Resistor R8 provides bias for U3 and R7 sets the

overall DC gain. Resistor R9, C19, R3 and C5 provide loop

compensation. A soft-ﬁnish capacitor (C20) eliminates output

overshoot.

Figure 44. 60 W Multiple Output Power Supply using TOP246.

1N4148

UF4003

UF5402

D11

MBR1045

D10

BYV32-200

T1 U2

LTV817

TL431

C20

22 µF

10 V

150 Ω

R12

10 k

C19

0.1 µF

R11

9.53

kΩ

R10

15.0

kΩ

3.3 kΩ

1 kΩ

2.2 nF

47 µF

50 V

330 µF

25 V

C11

390 µF

35 V

C14

1000 µF

25 V

30 V @

0.03 A

18 V @

0.5 A

12 V @

0.6 A

5 V @

3.2 A

3.3 V @

3 A

RTN

D1-D4

1N4007 V

3.15 A

RV1

275 V

14 mm

20 mH

0.8A

t°

6.8 Ω

47 µF

10 V

TOP246Y

D L

TOPSwitch-GX

2 MΩ

1/2 W

68 kΩ

2 W

10 Ω

RT1

10 Ω

1.7 A

68 µF

400 V

1 nF

400 V

1 µF

50 V

0.1 µF

PI-2693-081704

CONTROL

0.1 µF

50 V

X F

1N4937

VR1

P6KE170

C16

1000 µF

25 V

C13

1000 µF

25 V

C17

1000 µF

25 V

C15

220 µF

16 V

C18

220 µF

16 V

C12

100 µF

25 V

C10

100 µF

25 V

10 µF

50 V

3.3 µH

PERFORMANCE SUMMARY

Output Power: 45 W Cont./60 W Peak

Regulation:

3.3 V: ± 5%

5 V: ± 5%

12 V: ± 7%

18 V: ± 7%

30 V: ± 8%

Efficiency: ≥75%

No Load Consumption: 0.6 W

185-265 VAC

9.08 kΩ

TOP242-250

4/05

Processor Controlled Supply Turn On/Off

A low cost momentary contact switch can be used to turn

the TOPSwitch-GX power on and off under microprocessor

control, which may be required in some applications such as

printers. The low power remote OFF feature allows an

elegant implementation of this function with very few external

components, as shown in Figure 45. Whenever the push

button momentary contact switch P1 is closed by the user, the

optocoupler U3 is activated to inform the microprocessor of

this action. Initially, when the power supply is off (M pin is

ﬂoating), closing of P1 turns the power supply on by shorting

the M pin of the TOPSwitch-GX to SOURCE through a diode

(remote ON). When the secondary output voltage VCC is

established, the microprocessor comes alive and recognizes that

the switch P1 is closed through the switch status input that is

driven by the optocoupler U3 output. The microprocessor then

sends a power supply control signal to hold the power supply

in the on-state through the optocoupler U4. If the user presses

the switch P1 again to command a turn off, the microprocessor

detects this through the optocoupler U3 and initiates a shutdown

procedure that is product speciﬁc. For example, in the case of

the inkjet printer, the shutdown procedure may include safely

parking the print heads in the storage position. In the case of

products with a disk drive, the shutdown procedure may include

saving data or settings to the disk. After the shutdown procedure

is complete, when it is safe to turn off the power supply, the

microprocessor releases the M pin by turning the optocoupler

U4 off. If the manual switch and the optocouplers U3 and U4

are not located close to the M pin, a capacitor CM may be needed

to prevent noise coupling to the pin when it is open.

The power supply could also be turned on remotely through

a local area network or a parallel or serial port by driving the

optocoupler U4 input LED with a logic signal. Sometimes it is

easier to send a train of logic pulses through a cable (due to AC

coupling of cable, for example) instead of a DC logic level as

a wake up signal. In this case, a simple RC ﬁlter can be used

to generate a DC level to drive U4 (not shown in Figure 45).

This remote on feature can be used to wake up peripherals

such as printers, scanners, external modems, disk drives, etc.,

as needed from a computer. Peripherals are usually designed

to turn off automatically if they are not being used for a period

of time, to save power.

P1 P1 Switch

Status

Power

Supply

ON/OFF

Control

External

Wake-up

Signal

PI-2561-030805

VCC

(+5 V)

RETURN

CONTROL

MICRO-

PROCESSOR/

CONTROLLER

LOGIC

INPUT

LOGIC

OUTPUT

High Voltage

DC Input

TOPSwitch-GX

D M

S F

1N4148

LTV817A

6.8 kΩ

1 nF

100 kΩ

6.8 kΩ

LTV817A

27 kΩ

1N4148

47 µF

Figure 45. Remote ON/OFF using Microcontroller.

TOP242-250

4/05

In addition to using a minimum number of components,

TOPSwitch-GX provides many technical advantages in this

type of application:

1. Extremely low power consumption in the off mode: 80 mW

typical at 110 VAC and 160 mW typical at 230 VAC. This

is because, in the remote OFF mode, the TOPSwitch-GX

consumes very little power and the external circuitry does

not consume any current (either M, L or X pin is open) from

the high voltage DC input.

2. A very low cost, low voltage/current, momentary contact

switch can be used.

3. No debouncing circuitry for the momentary switch is

required. During turn-on, the start-up time of the power

supply (typically 10 ms to 20 ms) plus the microprocessor

initiation time act as a debouncing ﬁlter, allowing a turn-on

only if the switch is depressed ﬁrmly for at least the above

delay time. During turn-off, the microprocessor initiates

the shutdown sequence when it detects the ﬁrst closure of

the switch and subsequent bouncing of the switch has no

effect. If necessary, the microprocessor could implement

the switch debouncing in software during turn-off, or a ﬁlter

capacitor can be used at the switch status input.

4. No external current limiting circuitry is needed for the

operation of the U4 optocoupler output due to internal

limiting of M pin current.

5. No high voltage resistors to the input DC voltage rail are

required to power the external circuitry in the primary. Even

the LED current for U3 can be derived from the CONTROL

pin. This not only saves components and simpliﬁes layout,

but also eliminates the power loss associated with the high

voltage resistors in both ON and OFF states.

6. Robust design: There is no ON/OFF latch that can be

accidentally triggered by transients. Instead, the power

supply is held in the ON-state through the secondary-side

microprocessor.

TOP242-250

4/05

Function TOPSwitch-II TOPSwitch-GX Figures TOPSwitch-GX

Advantages

Soft-Start N/A* 10 ms • Limits peak current and voltage

component stresses during start-

• Eliminates external components

used for soft-start in most

applications

• Reduces or eliminates output

overshoot

External Current

Limit

N/A* Programmable 100%

to 30% of default

current limit

11,20,21,

24,25,27,

28,34,35,

38,39

• Smaller transformer

• Higher efﬁciency

• Allows power limiting (constant

overload power independent of

line voltage)

• Allows use of larger device for

lower losses, higher efﬁciency

and smaller heatsink

DCMAX 67% 78% 7 • Smaller input cap (wider dynamic

range)

• Higher power capability (when

used with RCD clamp for large

VOR)

• Allows use of Schottky secondary

rectiﬁer diode for up to 15 V

output for high efﬁciency

Line Feed-Forward

with DC MAX Reduction

N/A* 78% to 38% 7,11,17,

26,27,28,

31,40

• Rejects line ripple

Line OV Shutdown N/A* Single resistor

programmable

11,17,19,

26,27,28

31,33,40

• Increases voltage withstand

capability against line surge

Line UV Detection N/A* Single resistor

programmable

11,17,18,

26,27,28,

31,32,40

• Prevents auto-restart glitches

during power down

Switching Frequency 100 kHz ±10% 132 kHz ±6% 13,15 • Smaller transformer

• Below start of conducted EMI

limits

Table 4. Comparison Between TOPSwitch-II and TOPSwitch-GX (continued on next page). *Not available

Key Application Considerations

TOPSwitch-II vs. TOPSwitch-GX

Table 4 compares the features and performance differences

between TOPSwitch-GX and TOPSwitch-II. Many of the new

features eliminate the need for additional discrete components.

Other features increase the robustness of design, allowing cost

savings in the transformer and other power components.

TOP242-250

4/05

Function TOPSwitch-II TOPSwitch-GX Figures TOPSwitch-GX

Advantages

Switching Frequency

Option (Y, R and F

Packages)

N/A* 66 kHz ±7% 14,15 • Lower losses when using RC and

RCD snubber for noise reduction

in video applications

• Allows for higher efﬁciency in

standby mode

• Lower EMI (second harmonic

below 150 kHz)

Frequency Jitter N/A* ±4 kHz @ 132 kHz

±2 kHz @ 66 kHz

9,46 • Reduces conducted EMI

Frequency Reduction N/A* At a duty cycle below

10%

7 • Zero load regulation without

dummy load

• Low power consumption at

no-load

Remote ON/OFF N/A* Single transistor or

optocoupler interface

or manual switch

11,22,23,

24,25,26,

27,29,36,

37,38,39,

• Fast ON/OFF (cycle-by-cycle)

• Active-on or active-off control

• Low consumption in remote off

state

• Active-on control for fail-safe

• Eliminates expensive in-line

on/off switch

• Allows processor controlled turn

on/off

• Permits shutdown/wake-up of

peripherals via LAN or parallel

port

Synchronization N/A* Single transistor or

optocoupler interface

• Synchronization to external lower

frequency signal

• Starts new switching cycle on

demand

Thermal Shutdown 125 °C min.

Latched

Hysteretic 130 °C

min. shutdown (with

75 °C hysteresis)

• Automatic recovery from thermal

fault

• Large hysteresis prevents circuit

board overheating

Current Limit

Tolerance

±10% (@ 25 °C)

-8% (0 °C to

100 °C)

±7% (@ 25 °C)

-4% Typical

(0 °C to 100 °C)**

• 10% Higher power capability due

to tighter tolerance

DRAIN

Creepage

at Package

DIP 0.037” / 0.94 mm 0.137” / 3.48 mm • Greater immunity to arcing as a

result of build-up of dust, debris

and other contaminants

SMD 0.037” / 0.94 mm 0.137” / 3.48 mm

TO-220 0.046” / 1.17 mm 0.068” / 1.73 mm

DRAIN Creepage at

PCB for Y, R and F

Packages

0.045” / 1.14 mm

(R and F Package

N/A*)

0.113” / 2.87 mm

(performed leads)

• Performed leads accommodate

large creepage for PCB layout

• Easier to meet Safety (UL/VDE)

Table 4 (cont). Comparison Between TOPSwitch-II and TOPSwitch-GX. *Not available **Current limit set to internal maximum

TOP242-250

4/05

Function TOPSwitch-FX TOPSwitch-GX TOPSwitch-GX

Advantages

Light Load Operation Cycle skipping Frequency and duty

cycle reduction

• Improves light load efﬁciency

• Reduces no-load consumption

Line Sensing/Exter-

nally Set Current

Limit (Y, R and F

Packages)

Line sensing and

externally set current

limit mutually

exclusive (M pin)

Line sensing and

externally set current

limit possible simul-

taneously (functions

split onto L and X pins

• Additional design ﬂexibility allows all

features to be used simultaneously

Current Limit

Programming Range

100% to 40% 100% to 30% • Minimizes transformer core size in highly

continuous designs

P/G Package Current

Limits

Identical to Y

package

TOP243-246 P and

G packages internal

current limits reduced

• Matches device current limit to package

dissipation capability

• Allows more continuous design to lower

device dissipation (lower RMS currents)

Y/R/F Package

Current Limits

100% (R and F

package N/A*)

90% (for equivalent

RDS(ON))

• Minimizes transformer core size

• Optomizes efﬁciency for most applications

Thermal Shutdown 125 °C min.

70 °C hysteresis

130 °C min.

75 °C hysteresis

• Allows higher output powers in high

ambient temperature applications

Maximum Duty Cycle

Reduction Threshold

90 µA 60 µA • Reduces output line frequency ripple at

low line

• DCMAX reduction optimized for forward

designs using TOP248, TOP249 and

TOP250

Line Under-Voltage

Negative (turn-off)

Threshold

N/A* 40% of positive

(turn-on) threshold

• Provides a well deﬁned turn-off threshold

as the line voltage falls

Soft-Start 10 ms (duty cycle) 10 ms (duty cycle +

current limit)

• Gradually increasing current limit in

addition to duty cycle during soft-start

further reduces peak current and voltage

• Further reduces component stresses

during start up

TOPSwitch-FX vs. TOPSwitch-GX

Table 5 compares the features and performance differences

between TOPSwitch-GX and TOPSwitch-FX. Many of the new

features eliminate the need for additional discrete components.

Other features increase the robustness of design, allowing cost

savings in the transformer and other power components.

TOPSwitch-GX Design Considerations

Power Table

Data sheet power table (Table 1) represents the maximum

practical continuous output power based on the following

conditions: TOP242 to TOP246: 12 V output, Schottky output

diode, 150 V reﬂected voltage (VOR) and efﬁciency estimates

from curves contained in application note AN-29. TOP247

to TOP250: Higher output voltages, with a maximum output

current of 6 A.

For all devices, a 100 VDC minimum for 85-265 VAC and

250 VDC minimum for 230 VAC are assumed and sufﬁcient

heat sinking to keep device temperature ≤100 °C. Power

levels shown in the power table for the R package device

assume 6.45 cm2 of 610 g/m2 copper heat sink area in an

enclosed adapter, or 19.4 cm2 in an open frame.

TOPSwitch-GX Selection

Selecting the optimum TOPSwitch-GX depends upon required

maximum output power, efﬁciency, heat sinking constraints

and cost goals. With the option to externally reduce current

limit, a larger TOPSwitch-GX may be used for lower power

applications where higher efﬁciency is needed or minimal heat

sinking is available.

Table 5. Comparison Between TOPSwitch-FX and TOPSwitch-GX. *Not available

TOP242-250

4/05

Input Capacitor

The input capacitor must be chosen to provide the minimum DC

voltage required for the TOPSwitch-GX converter to maintain

regulation at the lowest speciﬁed input voltage and maximum

output power. Since TOPSwitch-GX has a higher DCMAX than

TOPSwitch-II, it is possible to use a smaller input capacitor.

For TOPSwitch-GX, a capacitance of 2 µF per watt is possible for

universal input with an appropriately designed transformer.

Primary Clamp and Output Reﬂected Voltage VOR

A primary clamp is necessary to limit the peak TOPSwitch-GX

drain to source voltage. A Zener clamp requires few parts and

takes up little board space. For good efﬁciency, the clamp

Zener should be selected to be at least 1.5 times the output

reﬂected voltage VOR, as this keeps the leakage spike conduction

time short. When using a Zener clamp in a universal input

application, a VOR of less than 135 V is recommended to allow

for the absolute tolerances and temperature variations of the

Zener. This will ensure efﬁcient operation of the clamp circuit

and will also keep the maximum drain voltage below the rated

breakdown voltage of the TOPSwitch-GX MOSFET.

A high VOR is required to take full advantage of the wider DCMAX

of TOPSwitch-GX. An RCD clamp provides tighter clamp

voltage tolerance than a Zener clamp and allows a VOR as high

as 150 V. RCD clamp dissipation can be minimized by reducing

the external current limit as a function of input line voltage (see

Figures 21 and 35). The RCD clamp is more cost effective than

the Zener clamp but requires more careful design (see Quick

Design Checklist).

Output Diode

The output diode is selected for peak inverse voltage, output

current, and thermal conditions in the application (including

heatsinking, air circulation, etc.). The higher DCMAX of

TOPSwitch-GX, along with an appropriate transformer turns

ratio, can allow the use of a 60 V Schottky diode for higher

efﬁciency on output voltages as high as 15 V (see Figure 41: A

12 V, 30 W design using a 60 V Schottky for the output diode).

Bias Winding Capacitor

Due to the low frequency operation at no-load a 1 µF bias

winding capacitor is recommended.

Soft-Start

Generally, a power supply experiences maximum stress at

start-up before the feedback loop achieves regulation. For a

period of 10 ms, the on-chip soft-start linearly increases the duty

cycle from zero to the default DCMAX at turn on. In addition,

the primary current limit increases from 85% to 100% over the

same period. This causes the output voltage to rise in an orderly

manner, allowing time for the feedback loop to take control of

the duty cycle. This reduces the stress on the TOPSwitch-GX

MOSFET, clamp circuit and output diode(s), and helps prevent

transformer saturation during start-up. Also, soft-start limits the

amount of output voltage overshoot and, in many applications,

eliminates the need for a soft-ﬁnish capacitor.

EMI

The frequency jitter feature modulates the switching frequency

over a narrow band as a means to reduce conducted EMI peaks

associated with the harmonics of the fundamental switching

frequency. This is particularly beneﬁcial for average detection

mode. As can be seen in Figure 46, the beneﬁts of jitter increase

with the order of the switching harmonic due to an increase in

frequency deviation.

The FREQUENCY pin of TOPSwitch-GX offers a switching

frequency option of 132 kHz or 66 kHz. In applications that

require heavy snubbers on the drain node for reducing high

-20

-10

0.15 1 10 30

Frequency (MHz)

Amplitude (dBµV)

PI-2576-010600

EN55022B (QP)

EN55022B (AV)

TOPSwitch-II (no jitter)

EN55022B (QP)

EN55022B (AV)

-20

-10

0.15 1 10 30

Frequency (MHz)

Amplitude (dBµV)

PI-2577-010600

TOPSwitch-GX (with jitter)

Figure 46a. TOPSwitch-II Full Range EMI Scan (100 kHz, No Jitter).

Figure 46b. TOPSwitch-GX Full Range EMI Scan (132 kHz, With

Jitter) with Identical Circuitry and Conditions.

TOP242-250

4/05

frequency radiated noise (for example, video noise sensitive

applications such as VCR, DVD, monitor, TV, etc.), operating

at 66 kHz will reduce snubber loss resulting in better efﬁciency.

Also, in applications where transformer size is not a concern,

use of the 66 kHz option will provide lower EMI and higher

efﬁciency. Note that the second harmonic of 66 kHz is still

below 150 kHz, above which the conducted EMI speciﬁcations

get much tighter.

For 10 W or below, it is possible to use a simple inductor in

place of a more costly AC input common mode choke to meet

worldwide conducted EMI limits.

Transformer Design

It is recommended that the transformer be designed for

maximum operating ﬂux density of 3000 Gauss and a peak ﬂux

density of 4200 Gauss at maximum current limit. The turns ratio

should be chosen for a reﬂected voltage (VOR) no greater than

135 V when using a Zener clamp, or 150 V (max) when using

an RCD clamp with current limit reduction with line voltage

(overload protection).

For designs where operating current is signiﬁcantly lower than

the default current limit, it is recommended to use an externally

set current limit close to the operating peak current to reduce peak

ﬂux density and peak power (see Figures 20 and 34). In most

applications, the tighter current limit tolerance, higher switching

frequency and soft-start features of TOPSwitch-GX contribute

to a smaller transformer when compared to TOPSwitch-II.

Standby Consumption

Frequency reduction can signiﬁcantly reduce power loss at

light or no load, especially when a Zener clamp is used. For

very low secondary power consumption, use a TL431 regulator

for feedback control. Alternately, switching losses can be

signiﬁcantly reduced by changing from 132 kHz in normal

operation to 66 kHz under light load conditions.

TOPSwitch-GX Layout Considerations

As TOPSwitch-GX has additional pins and operates at

much higher power levels compared to previous TOPSwitch

families, the following guidelines should be carefully

followed.

Primary Side Connections

Use a single point (Kelvin) connection at the negative terminal

of the input ﬁlter capacitor for the TOPSwitch-GX SOURCE

pin and bias winding return. This improves surge capabilities

by returning surge currents from the bias winding directly to

the input ﬁlter capacitor.

The CONTROL pin bypass capacitor should be located as

close as possible to the SOURCE and CONTROL pins and its

SOURCE connection trace should not be shared by the main

MOSFET switching currents. All SOURCE pin referenced

components connected to the MULTI-FUNCTION, LINE-

SENSE or EXTERNAL CURRENT LIMIT pins should

also be located closely between their respective pin and

SOURCE. Once again, the SOURCE connection trace of these

components should not be shared by the main MOSFET

switching currents. It is very critical that SOURCE pin

switching currents are returned to the input capacitor negative

terminal through a seperate trace that is not shared by the

components connected to CONTROL, MULTI-FUNCTION,

LINE-SENSE or EXTERNAL CURRENT LIMIT pins. This

is because the SOURCE pin is also the controller ground

reference pin.

Any traces to the M, L or X pins should be kept as short as

possible and away from the DRAIN trace to prevent noise

coupling. LINE-SENSE resistor (R1 in Figures 47-49) should

be located close to the M or L pin to minimize the trace length

on the M or L pin side.

In addition to the 47 µF CONTROL pin capacitor, a high

frequency bypass capacitor in parallel may be used for better

noise immunity. The feedback optocoupler output should

also be located close to the CONTROL and SOURCE pins of

TOPSwitch-GX.

Y-Capacitor

The Y-capacitor should be connected close to the secondary

output return pin(s) and the positive primary DC input pin of

the transformer.

Heat Sinking

The tab of the Y package (TO-220) or F package (TO-262)

is internally electrically tied to the SOURCE pin. To avoid

circulating currents, a heat sink attached to the tab should not

be electrically tied to any primary ground/source nodes on the

PC board.

When using a P (DIP-8), G (SMD-8) or R (TO-263) package,

a copper area underneath the package connected to the

SOURCE pins will act as an effective heat sink. On double

sided boards (Figure 49), top side and bottom side areas

connected with vias can be used to increase the effective heat

sinking area.

In addition, sufﬁcient copper area should be provided at

the anode and cathode leads of the output diode(s) for heat

sinking.

In Figures 47, 48 and 49, a narrow trace is shown between

the output rectiﬁer and output ﬁlter capacitor. This trace acts

as a thermal relief between the rectiﬁer and ﬁlter capacitor to

prevent excessive heating of the capacitor.

TOP242-250

4/05

TOP VIEW

PI-2670-042301

Y1-

Capacitor

Opto-

coupler

R2 +- DC

Out

Input Filter Capacitor Output Filter Capacitor

Output Rectifier

Safety Spacing

Maximize hatched copper

areas ( ) for optimum

heat sinking

PRI

SEC

BIAS

TOPSwitch-GX

Figure 47. Layout Consideratiions for TOPSwitch-GX using P or G Package.

Input Filter Capacitor

Heat Sink

Safety Spacing

Opto-

coupler

+- DC

Out

Output Filter Capacitor

SEC

Maximize hatched copper

areas ( ) for optimum

heat sinking

Y1-

Capacitor

PI-2669-042301

TOP VIEW

TOPSwitch-GX

Output Rectifier

Figure 48. Layout Consideratiions for TOPSwitch-GX using Y or F Package.

TOP242-250

4/05

Quick Design Checklist

As with any power supply design, all TOPSwitch-GX designs

should be veriﬁed on the bench to make sure that components

speciﬁcations are not exceeded under worst case conditions. The

following minimum set of tests is strongly recommended:

1. Maximum drain voltage – Verify that peak VDS does not

exceed 675 V at highest input voltage and maximum

overload output power. Maximum overload output power

occurs when the output is overloaded to a level just before the

power supply goes into auto-restart (loss of regulation).

2. Maximum drain current – At maximum ambient temperature,

maximum input voltage and maximum output load, verify

drain current waveforms at start-up for any signs of

transformer saturation and excessive leading edge current

spikes. TOPSwitch-GX has a leading edge blanking time of

220 ns to prevent premature termination of the ON-cycle.

Verify that the leading edge current spike is below the

allowed current limit envelope (see Figure 52) for the

drain current waveform at the end of the 220 ns blanking

period.

3. Thermal check – At maximum output power, minimum

input voltage and maximum ambient temperature, verify

that temperature specifications are not exceeded for

TOPSwitch-GX, transformer, output diodes and output

capacitors. Enough thermal margin should be allowed for

the part-to-part variation of the RDS(ON) of TOPSwitch-GX,

as speciﬁed in the data sheet. The margin required can

either be calculated from the tolerances or it can be

accounted for by connecting an external resistance in

series with the DRAIN pin and attached to the same

heatsink, having a resistance value that is equal to the

difference between the measured RDS(ON) of the device

under test and the worst case maximum speciﬁcation.

Design Tools

For a discussion on utilizing TOP248, TOP249 and TOP250

in forward converter conﬁgurations, please refer to the

TOPSwitch-GX Forward Design Methodology Application

Note.

Up-to-date information on design tools can be found at the

Power Integrations website: www.powerint.com

+- DC

Out

PI-2734-043001

Safety Spacing

Y1-

Capacitor

Solder Side

Component Side

Opto-

coupler

Output Filter Capacitors

Maximize hatched copper

areas ( ) for optimum

heat sinking

TOP VIEW

Input Filter

Capacitor

R1a - 1c

PRI

PRI SEC

BIAS

TOPSwitch-GX

Figure 49. Layout Considerations for TOPSwitch-GX using R Package.

TOP242-250

4/05

Parameter Symbol

Conditions

SOURCE = 0 V; TJ = -40 to 125 °C

See Figure 53

(Unless Otherwise Speciﬁed)

Min Typ Max Units

CONTROL FUNCTIONS

Switching

Frequency

(average)

fOSC

IC = 3 mA;

TJ = 25 °C

FREQUENCY Pin

Connected to SOURCE 124 132 140

kHz

FREQUENCY Pin

Connected to CONTROL 61.5 66 70.5

Duty Cycle at

ONSET of

Frequency

Reduction

DC(ONSET) 10 %

Switching

Frequency near

0% Duty Cycle

fOSC(DMIN)

132 kHz Operation 30

kHz

66 kHz Operation 15

Frequency Jitter

Deviation ∆f132 kHz Operation ±4 kHz

66 kHz Operation ±2

Frequency Jitter

Modulation Rate fM250 Hz

ABSOLUTE MAXIMUM RATINGS(1,4)

DRAIN Voltage .................................. ................ -0.3 V to 700 V

DRAIN Peak Current: TOP242......................................0.72 A

TOP243....................................... 1.44 A

TOP244..........................................2.16 A

TOP245....................................... 2.88 A

TOP246..........................................4.32 A

TOP247..........................................5.76 A

TOP248..........................................7.20 A

TOP249..........................................8.64 A

TOP250 ........................................10.08 A

CONTROL Voltage ................................................ -0.3 V to 9

VCONTROL Current .................................................... 100 mA

LINE SENSE Pin Voltage ................................... -0.3 V to 9 V

CURRENT LIMIT Pin Voltage ........................-0.3 V to 4.5 V

MULTI-FUNCTION Pin Voltage ........................- 0.3 V to 9 V

FREQUENCY Pin Voltage ..................................-0.3 V to 9 V

Storage Temperature ..................................... -65 °C to 150 °C

Operating Junction Temperature(2) ................ -40 °C to 150 °C

Lead Temperature(3) ...................................................... 260 °C

Notes:

1. All voltages referenced to SOURCE, TA = 25 °C.

2. Normally limited by internal circuitry.

3. 1/16 in. from case for 5 seconds.

4. Maximum ratings speciﬁed may be applied one at a time,

without causing permanent damage to the product.

Exposure to Absolute Maximum Rating conditions for

extended periods of time may affect product reliability.

THERMAL IMPEDANCE

Thermal Impedance: Y or F Package:

(θJA)(1) .......................... ..................... 80 °C/W

(θJC)(2) ................................................ . 2 °C/W

P or G Package:

(θJA) ............................ 70 °C/W(3); 60 °C/W(4)

(θJC)(5) ................................................ 11 °C/W

R Package:

(θJA) ..........80 °C/W(7); 40 °C/W(4); 30 °C/W(6)

(θJC)(5) .................................................. 2 °C/W

Notes:

1. Free standing with no heatsink.

2. Measured at the back surface of tab.

3. Soldered to 0.36 sq. in. (232 mm2), 2 oz. (610 g/m2)

copper clad.

4. Soldered to 1 sq. in. (645 mm2), 2 oz. (610 g/m2) copper clad.

5. Measured on the SOURCE pin close to plastic interface.

6. Soldered to 3 sq. in. (1935 mm2), 2 oz. (610 g/m2) copper clad.

7. Soldered to foot print area, 2 oz. (610 g/m2) copper clad.

TOP242-250

4/05

Parameter Symbol

Conditions

SOURCE = 0 V; TJ = -40 to 125 °C

See Figure 53

(Unless Otherwise Speciﬁed)

Min Typ Max Units

CONTROL FUNCTIONS (cont.)

Maximum Duty

Cycle DCMAX IC = ICD1

IL ≤ IL(DC) or IM ≤ IM(DC) 75 78 83

IL or IM = 190 µA

TOP242-247 28 38 50

IL or IM = 100 µA

TOP242-247 66.5

IL = 190 µA

TOP248-250 33 41.3 49.5

IL = 100 µA

TOP248-250 60 66.8 73.5

Soft-Start Time tSOFT TJ = 25 °C; DCMIN to DCMAX 10 15 ms

PWM Gain DCreg IC = 4 mA; TJ = 25 °C -28 -23 -18 %/mA

PWM Gain

Temperature Drift See Note A -0.01 %/mA/°C

External Bias

Current IBSee Figure 7

TOP242-245 1.2 2.0 3.0

mATOP246-249 1.6 2.6 4.0

TOP250 1.7 2.7 4.2

CONTROL

Current at 0%

Duty Cycle

IC(OFF) TJ = 25 °C

TOP242-245 6.0 7.0

TOP246-249 6.6 8.0

TOP250 7.3 8.5

Dynamic

Impedance ZC

IC = 4 mA; TJ = 25 °C

See Figure 51 10 15 22 Ω

Dynamic

Impedance

Temperature Drift

0.18 %/°C

CONTROL Pin

Internal Filter Pole 7 kHz

SHUTDOWN/AUTO-RESTART

CONTROL Pin

Charging Current IC(CH) TJ = 25 °C VC = 0 V -5.0 -3.5 -2.0 mA

VC = 5 V -3.0 -1.8 -0.6

Charging Current

Temperature Drift See Note A 0.5 %/°C

Auto-Restart

Upper Threshold

Voltage

VC(AR)U 5.8 V

Auto-Restart

Lower Threshold

Voltage

VC(AR)L 4.5 4.8 5.1 V

TOP242-250

4/05

Parameter Symbol

Conditions

SOURCE = 0 V; TJ = -40 to 125 °C

See Figure 53

(Unless Otherwise Speciﬁed)

Min Typ Max Units

SHUTDOWN/AUTO-RESTART (cont.)

Auto-Restart

Hysteresis Voltage VC(AR)hyst 0.8 1.0 V

Auto-Restart Duty

Cycle DC(AR) 4 8 %

Auto-Restart

Frequency f(AR) 1.0 Hz

MULTI-FUNCTION (M), LINE-SENSE (L) AND EXTERNAL CURRENT LIMIT (X) INPUTS

Line Under-

Voltage Threshold

Current and Hys-

teresis (M or L Pin)

IUV TJ = 25 °C

Threshold 44 50 54 µA

Hysteresis 30 µA

Line Overvoltage

or Remote ON/OFF

Threshold Current

and Hysteresis

(M or L Pin)

IOV TJ = 25 °C

Threshold 210 225 240 µA

Hysteresis 8 µA

L Pin Voltage

Threshold VL(TH) 0.5 1.0 1.6 V

Remote ON/OFF

Negative

Threshold Current

and Hysteresis

(M or X Pin)

IREM (N) TJ = 25 °C

Threshold -35 -27 -20 µA

Hysteresis 5 µA

L or M Pin Short

Circuit Current

IL(SC) or

IM(SC)

VL, VM = VC300 400 520 µA

X or M Pin Short

Circuit Current

IX(SC) or

IM(SC)

VX, VM = 0 V Normal Mode -300 -240 -180 µA

Auto-Restart Mode -110 -90 -70

L or M Pin Voltage

(Positive Current) VL, VM

IL or IM = 50 µA 1.90 2.50 3.00 V

IL or IM = 225 µA 2.30 2.90 3.30

X Pin Voltage

(Negative Current) VX

IX = -50 µA 1.26 1.33 1.40 V

IX = -150 µA 1.18 1.24 1.30

M Pin Voltage

(Negative Current) VM

IM = -50 µA 1.24 1.31 1.39 V

IM = -150 µA 1.13 1.19 1.25

TOP242-250

4/05

Parameter Symbol

Conditions

SOURCE = 0 V; TJ = -40 to 125 °C

See Figure 53

(Unless Otherwise Speciﬁed)

Min Typ Max Units

MULTI-FUNCTION, LINSE-SENSE AND EXTERNAL CURRENT LIMIT INPUTS (cont.)

Maximum Duty

Cycle Reduction

Onset Threshold

Current

IL(DC) or

IM(DC)

TJ = 25 °C 40 60 75 µA

Remote OFF

DRAIN Supply

Current

ID(RMT)

See Figure 71

VDRAIN = 150 V

X, L or M Pin

Floating 0.6 1.0

L or M Pin Shorted

to CONTROL 1.0 1.6

Remote ON Delay tR(ON)

From Remote ON to Drain Turn-On

See Note B 2.5 µs

Remote OFF

Setup Time tR(OFF)

Minimum Time Before Drain Turn-On

to Disable Cycle, See Note B 2.5 µs

FREQUENCY INPUT

FREQUENCY Pin

Threshold Voltage VFSee Note B 2.9 V

FREQUENCY Pin

Input Current IFVF = VC10 40 100 µA

CIRCUIT PROTECTION

Self Protection

Current Limit

(See Note C)

ILIMIT

TOP242 P/G

TOP242 Y/R/F

TJ = 25 °C

Internal

di/dt = 90 mA/µs0.418 0.45 0.481

TOP243 P/G

TJ = 25 °C

Internal

di/dt = 150 mA/µs0.697 0.75 0.802

TOP243 Y/R/F

TJ = 25 °C

Internal

di/dt = 180 mA/µs0.837 0.90 0.963

TOP244 P/G

TJ = 25 °C

Internal

di/dt = 200 mA/µs0.930 1.00 1.070

TOP244 Y/R/F

TJ = 25 °C

Internal

di/dt = 270 mA/µs1.256 1.35 1.445

TOP245 P

TJ = 25 °C

Internal

di/dt = 220 mA/µs1.02 1.10 1.18

TOP245 Y/R/F

TJ = 25 °C

Internal

di/dt = 360 mA/µs1.674 1.80 1.926

TOP246 P

TJ = 25 °C

Internal

di/dt = 270 mA/µs1.256 1.35 1.445

TOP246 Y/R/F

TJ = 25 °C

Internal

di/dt = 540 mA/µs2.511 2.70 2.889

TOP247 Y/R/F

TJ = 25 °C

Internal

di/dt = 720 mA/µs3.348 3.60 3.852

TOP242-250

4/05

Parameter Symbol

Conditions

SOURCE = 0 V; TJ = -40 to 125 °C

See Figure 53

(Unless Otherwise Speciﬁed)

Min Typ Max Units

CIRCUIT PROTECTION (cont.)

Self Protection

Current Limit

(See Note C)

ILIMIT

TOP248 Y/R/F

TJ = 25 °C

Internal

di/dt = 900 mA/µs4.185 4.50 4.815

TOP249 Y/R/F

TJ = 25 °C

Internal

di/dt = 1080 mA/µs5.022 5.40 5.778

TOP250 Y/R/F

TJ = 25 °C

Internal

di/dt = 1260 mA/µs5.859 6.30 6.741

Initial Current Limit IINIT See Note B

≤85 VAC

(Rectiﬁed Line Input)

0.75 x

ILIMIT(MIN) A

265 VAC

(Rectiﬁed Line Input)

0.6 x

ILIMIT(MIN)

Leading Edge

Blanking Time tLEB

See Figure 52

TJ = 25 °C, IC = 4 mA 220 ns

Current Limit

Delay tIL(D) IC = 4 mA 100 ns

Thermal Shut-

down Temperature 130 140 150 °C

Thermal Shut-

down Hysteresis Ω 75 °C

Power-Up Reset

Threshold Voltage VC(RESET) Figure 53, S1 Open 1.75 3.0 4.25 V

OUTPUT

ON-State

Resistance RDS(ON)

TOP242

ID = 50 mA

TJ = 25 °C 15.6 18.0

Ω

TJ = 100 °C 25.7 30.0

TOP243

ID = 100 mA

TJ = 25 °C 7.80 9.00

TJ = 100 °C 12.9 15.0

TOP244

ID = 150 mA

TJ = 25 °C 5.20 6.00

TJ = 100 °C 8.60 10.0

TOP245

ID = 200 mA

TJ = 25 °C 3.90 4.50

TJ = 100 °C 6.45 7.50

TOP246

ID = 300 mA

TJ = 25 °C 2.60 3.00

TJ = 100 °C 4.30 5.00

TOP247

ID = 400 mA

TJ = 25 °C 1.95 2.25

TJ = 100 °C 3.22 3.75

TOP248

ID = 500 mA

TJ = 25 °C 1.56 1.80

TJ = 100 °C 2.58 3.00

TOP242-250

4/05

NOTES:

A. For speciﬁcations with negative values, a negative temperature coefﬁcient corresponds to an increase in

magnitude with increasing temperature, and a positive temperature coefﬁcient corresponds to a decrease in

magnitude with increasing temperature.

B. Guaranteed by characterization. Not tested in production.

C. For externally adjusted current limit values, please refer to Figures 54b, 55b and 56b (Current Limit vs. External

Current Limit Resistance) in the Typical Performance Characteristics section. The tolerance speciﬁed is only valid

at full current limit.

D. Breakdown voltage may be checked against minimum BVDSS speciﬁcation by ramping the DRAIN pin voltage up

to but not exceeding minimum BVDSS.

E. It is possible to start up and operate

TOPSwitch-GX

at DRAIN voltages well below 36 V. However, the CONTROL

pin charging current is reduced, which affects start-up time, auto-restart frequency, and auto-restart duty cycle.

Refer to Figure 68, the characteristic graph on CONTROL pin charge current (IC) vs. DRAIN voltage for low

voltage operation characteristics.

Parameter Symbol

Conditions

SOURCE = 0 V; TJ = -40 to 125 °C

See Figure 53

(Unless Otherwise Speciﬁed)

Min Typ Max Units

OUTPUT (cont.)

ON-State

Resistance RDS(ON)

TOP249

ID = 600 mA

TJ = 25 °C 1.30 1.50

Ω

TJ = 100 °C 2.15 2.50

TOP250

ID = 700 mA

TJ = 25 °C 1.10 1.28

TJ = 100 °C 1.85 2.15

OFF-State Drain

Leakage Current IDSS

VL, VM = Floating; IC = 4 mA

VDS = 560 V; TJ = 125 °C470 µA

Breakdown

Voltage BVDSS

VL, VM = Floating; IC = 4 mA

See Note D, TJ = 25 °C700 V

Rise Time tRMeasured in a Typical Flyback

Converter Application

100 ns

Fall Time tF50 ns

SUPPLY VOLTAGE CHARACTERISTICS

DRAIN Supply

Voltage See Note E 36 V

Shunt Regulator

Voltage VC(SHUNT) IC = 4 mA 5.60 5.85 6.10 V

Shunt Regulator

Temperature Drift ±50 ppm/°C

Control Supply/

Discharge Current

ICD1

Output MOSFET

Enabled

VX, VL, VM = 0 V

TOP242-245 1.0 1.6 2.5

TOP246-249 1.2 2.2 3.2

TOP250 1.3 2.4 3.65

ICD2

Output MOSFET

Disabled

VX, VL, VM = 0 V

0.3 0.6 1.3

TOP242-250

4/05

PI-2039-033001

DRAIN

VOLTAGE

0 V

90%

10%

90%

D = t1

Figure 50. Duty Cycle Measurement.

120

100

0 2 4 6 8 10

CONTROL Pin Voltage (V)

CONTROL Pin Current (mA)

Slope

Dynamic

Impedance =

PI-1939-091996

0.8

1.3

1.2

1.1

0.9

0.8

1.0

0 1 2 6 83

Time (µs)

DRAIN Current (normalized)

PI-2022-033001

4 5 7

0.7

0.6

0.5

0.4

0.3

0.2

0.1

ILIMIT(MAX) @ 25 °C

ILIMIT(MIN) @ 25 °C

IINIT(MIN) @ 85 VAC

IINIT(MIN) @ 265 VAC

tLEB (Blanking Time)

PI-2631-081204

5-50 V

40 V

0.1 µF47 µF

470 Ω

5 W

Y or R Package (X and L Pins) P or G Package (M Pin)

470 Ω

0-100 kΩ

0-60 kΩ

0-100 kΩ

NOTES: 1. This test circuit is not applicable for current limit or output characteristic measurements.

2. For P and G packages, short all SOURCE pins together.

SF X

CONTROL

TOPSwitch-GX

0-15 V

Figure 51. CONTROL Pin I-V Characteristic. Figure 52. Drain Current Operating Envelope.

Figure 53. TOPSwitch-GX General Test Circuit.

TOP242-250

4/05

Figure 54a. Current Limit vs. X or M Pin Current (see Figures 55a and 56a for TOP245P and TOP246P).

The following precautions should be followed when testing

TOPSwitch-GX by itself outside of a power supply. The

schematic shown in Figure 53 is suggested for laboratory testing

of TOPSwitch-GX.

When the DRAIN pin supply is turned on, the part will be

in the auto-restart mode. The CONTROL pin voltage will be

oscillating at a low frequency between 4.8 V and 5.8 V and

the drain is turned on every eigth cycle of the CONTROL pin

oscillation. If the CONTROL pin power supply is turned on

while in this auto-restart mode, there is only a 12.5% chance

that the CONTROL pin oscillation will be in the correct state

(drain active state) so that the continuous drain voltage waveform

may be observed. It is recommended that the VC power supply

be turned on ﬁrst and the DRAIN pin power supply second if

continuous drain voltage waveforms are to be observed. The

12.5% chance of being in the correct state is due to the divide-

by-8 counter. Temporarily shorting the CONTROL pin to the

SOURCE pin will reset TOPSwitch-GX, which then will come

up in the correct state.

BENCH TEST PRECAUTIONS FOR EVALUATION OF ELECTRICAL CHARACTERISTICS

Typical Performance Characteristics

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

100

120

140

160

180

200

-250 -200 -150 -100 -50

IX or IM (µA)

Current Limit (A)

di/dt (mA/µs)

PI-2653-031904

Scaling Factors:

TOP242 P/G/Y/R/F: .45

TOP243 P/G: .75

TOP243 Y/R/F: .90

TOP244 P/G: 1

TOP244 Y/R/F: 1.35

TOP245 Y/R/F: 1.80

TOP246 Y/R/F: 2.70

TOP247 Y/R/F: 3.60

TOP248 Y/R/F 4.50

TOP249 Y/R/F: 5.40

TOP250 Y/R/F: 6.32

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

100

120

140

160

180

200

0 5K 10K 15K 20K 25K 30K 35K 40K

External Current Limit Resistor RIL (Ω)

Current Limit (A)

di/dt (mA/µs)

PI-2652-042303

45K

Maximum and minimum levels

are based on characterization.

Minimum

Typical

Maximum

Scaling Factors:

TOP242 P/G/Y/R/F: .45

TOP243 P/G: .75

TOP243 Y/R/F: .90

TOP244 P/G: 1

TOP244 Y/R/F: 1.35

TOP245 Y/R/F: 1.80

TOP246 Y/R/F: 2.70

TOP247 Y/R/F: 3.60

TOP248 Y/R/F 4.50

TOP249 Y/R/F: 5.40

TOP250 Y/R/F: 6.32

Figure 54b. Current Limit vs. External Current Limit Resistance (see Figures 55b and 56b for TOP245P and

TOP246P).

TOP242-250

4/05

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

-250 -200 -150 -100 -50

IM (µA)

Current Limit (A)

PI-3652-031904

Scaling Factor:

TOP245P: 1.1

100

120

140

160

180

200

di/dt (mA/µs)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

100

120

140

160

180

200

0 5K 10K 15K 20K 25K 30K 35K 40K

External Current Limit Resistor RIL (Ω)

Current Limit (A)

di/dt (mA/µs)

PI-3651-031804

45K

Measured at 25 °C.

Scaling Factor:

TOP245P: 1.1

Typical

Refer to MULTIFUNCTION (M) Pin

Operation section

.70

.80

.75

.85

.90

1.00

.95

1.05

1.10

1.15

1.20

1.25

0 5K 10K 15K 20K 25K 30K 35K 40K

External Current Limit Resistor RIL (Ω)

Current Limit (Normalized to 25 °C)

PI-3653-073003

45K

0 °C

100 °C

25 °C

Figure 55b. Current Limit vs. External Current Limit Resistance (TOP245P only).

Figure 55c. External Current Limit vs. External Current Limit Resistance at 0 °C, 25 °C and 100 °C Junction

Temperature (TOP245P only).

Figure 55a. Current Limit vs. MULTI-FUNCTION Pin Current (TOP245P only).

TOP242-250

4/05

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

100

120

140

160

180

200

-250 -200 -150 -100 -50

IM (µA)

Current Limit (A)

di/dt (mA/µs)

PI-3724-012704

Scaling Factor:

TOP246P: 1.35

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

0 5K 10K 15K 20K 25K 30K 35K 40K

External Current Limit Resistor RIL (Ω)

Current Limit (A)

45K

Measured at 25 °C.

Scaling Factor:

TOP246P: 1.35

Typical

100

120

140

160

180

200

di/dt (mA/µs)

PI-3725-031804

Refer to MULTIFUNCTION (M) Pin

Operation section

.70

.80

.75

.85

.90

1.00

.95

1.05

1.10

1.15

1.20

1.25

0 5K 10K 15K 20K 25K 30K 35K 40K

External Current Limit Resistor RIL (Ω)

Current Limit (Normalized to 25 °C)

PI-3726-100703

45K

0 °C

100 °C

25 °C

Figure 56a. Current Limit vs. MULTI-FUNCTION Pin Current (TOP246P only).

Figure 56b. Current Limit vs. External Current Limit Resistance (TOP246P only).

Figure 56c. External Current Limit vs. External Current Limit Resistance at 0 °C, 25 °C and 100 °C Junction

Temperature (TOP246P only).

TOP242-250

4/05

Typical Performance Characteristics (cont.)

1.1

1.0

0.9

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

Breakdown Voltage

(Normalized to 25 °C)

PI-176B-033001

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-1123A-033001

Output Frequency

(Normalized to 25 °C)

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-2555-033001

Current Limit

(Normalized to 25 °C)

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-2554-081204

Current Limit

(Normalized to 25 °C)

Use for TOP242-250 Y/R/F

packages and TOP242-244 P/G

packages only. See Figures 55c

and 56c for TOP245P and

TOP246P.

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-2553-033001

Overvoltage Threshold

(Normalized to 25 °C)

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-2552-033001

Under-Voltage Threshold

(Normalized to 25 °C)

Figure 57. Breakdown Voltage vs. Temperature. Figure 58. Frequency vs. Temperature.

Figure 59. Internal Current Limit vs. Temperature. Figure 60. External Current Limit vs. Temperature with

RIL = 12 kΩ.

Figure 61. Overvoltage Threshold vs. Temperature. Figure 62. Under-Voltage Threshold vs. Temperature.

TOP242-250

4/05

Typical Performance Characteristics (cont.)

Figure 63a. LINE-SENSE Pin Voltage vs. Current.

6.0

4.5

5.5

5.0

2.0

0 100 200 300 400

LINE-SENSE Pin Current (µA)

LINE SENSE Pin Voltage (V)

PI-2688-102700

3.0

2.5

3.5

4.0

1.6

1.0

1.4

1.2

-240 -180 -60-120 0

EXTERNAL CURRENT LIMIT Pin Current (µA)

EXTERNAL CURRENT LIMIT

Pin Voltage (V)

PI-2689-102300

0.4

0.2

0.6

0.8

VX = 1.33 - IXx 0.66 kΩ

-200 µA ≤ IX ≤ -25 µA

-300 -200 -100 0 100 200 300 400 500

PI-2542-102700

MULTI-FUNCTION Pin Voltage (V)

MULTI-FUNCTION Pin Current (µA)

See

Expanded

Version

1.2

1.4

1.6

0.4

0.6

0.2

0.8

1.0

-300 -200 -150 -50-250 -100 0

MULTI-FUNCTION Pin Voltage (V)

PI-2541-102700

MULTI-FUNCTION Pin Current (µA)

VM = 1.37 - IMx 1 kΩ

-200 µA ≤ IM ≤ -25 µA

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-2562-033001

CONTROL Current

(Normalized to 25 °C)

1.2

1.0

0.8

0.6

0.4

0.2

-50 -25 0 25 50 75 100 125 150

Junction Temperature (°C)

PI-2563-033001

Onset Threshold Current

(Normalized to 25 °C)

Figure 63b. EXTERNAL CURRENT LIMIT Pin Voltage

vs. Current.

Figure 64a. MULTI-FUNCTION Pin Voltage vs. Current. Figure 64b. MULTI-FUNCTION Pin Voltage vs. Current

(Expanded).

Figure 65. Control Current Out at 0% Duty Cycle

vs. Temperaure.

Figure 66. Max. Duty Cycle Reduction Onset Threshold

Current vs. Temperature.

TOP242-250

4/05

Typical Performance Characteristics (cont.)

Figure 67. Output Characteristics. Figure 68. IC vs. DRAIN Voltage.

0 2 4 6 8 10 12 14 16 18 20

DRAIN Voltage (V)

DRAIN Current (A)

PI-2645-010802

TCASE = 25 °C

TCASE = 100 °C

3TOP250 1.17

TOP249 1.00

TOP248 0.83

TOP247 0.67

TOP246 0.50

TOP245 0.33

TOP244 0.25

TOP243 0.17

TOP242 0.08

Scaling Factors:

1.2

1.6

0 20 40 60 80 100

DRAIN Voltage (V)

CONTROL Pin

Charging Current (mA)

PI-2564-101499

0.4

0.8

VC = 5 V

0 100 200 300 400 500 600

100

1000

10000

PI-2646-010802

Drain Voltage (V)

DRAIN Capacitance (pF)

TOP250 1.17

TOP249 1.00

TOP248 0.83

TOP247 0.67

TOP246 0.50

TOP245 0.33

TOP244 0.25

TOP243 0.17

TOP242 0.08

Scaling Factors:

600

400

500

200

100

300

0 200100 400 500300 600

DRAIN Voltage (V)

Power (mW)

PI-2650-020802

TOP250 1.17

TOP249 1.00

TOP248 0.83

TOP247 0.67

TOP246 0.50

TOP245 0.33

TOP244 0.25

TOP243 0.17

TOP242 0.08

Scaling Factors:

1.2

0.8

1.0

-50 0 50 100 150

Junction Temperature (°C)

Remote OFF DRAIN Supply Current

(Normalized to 25 °C)

PI-2690-102700

0.2

0.4

0.6

Figure 69. COSS vs. DRAIN Voltage. Figure 70. DRAIN Capacitance Power.

Figure 71. Remote OFF DRAIN Supply Current vs.

Temperature.

TOP242-250

4/05

PART ORDERING INFORMATION

TOPSwitch

Product Family

GX Series Number

Package Identiﬁer

G Plastic SMD-8B (TOP242-244 only)

P Plastic DIP-8B (TOP242-246 only)

Y Plastic TO-220-7C

R Plastic TO-263-7C (available only with TL option)

F Plastic TO-262-7C

Lead Finish

Blank Standard (Sn Pb)

N Pure Matte Tin (Pb-Free) (P, G, Y & F Packages)

Tape & Reel and Other Options

Blank Standard Conﬁgurations

TL Tape & Reel, (G Package: 1000 min., R Package: 750 min.)

TOP 242 G N - TL

TOP242-250

4/05

PI-2644-122004

Notes:

1. Controlling dimensions are inches. Millimeter

dimensions are shown in parentheses.

2. Pin numbers start with Pin 1, and continue from left

to right when viewed from the front.

3. Dimensions do not include mold flash or other

protrusions. Mold flash or protrusions shall not

exceed .006 (.15mm) on any side.

4. Minimum metal to metal spacing at the package

body for omitted pin locations is .068 in. (1.73 mm).

5. Position of terminals to be measured at a location

.25 (6.35) below the package body.

6. All terminals are solder plated.

Y07C

PIN 1 PIN 7

MOUNTING HOLE PATTERN

.050 (1.27)

.150 (3.81)

.050 (1.27)

.150 (3.81)

.050 (1.27)

.100 (2.54)

.180 (4.58)

.200 (5.08)

PIN 1

.010 (.25) M

.461 (11.71)

.495 (12.57)

.390 (9.91)

.420 (10.67)

.146 (3.71)

.156 (3.96)

.860 (21.84)

.880 (22.35)

.024 (.61)

.034 (.86)

.068 (1.73) MIN

.050 (1.27) BSC

.150 (3.81) BSC

.108 (2.74) REF

PIN 1 & 7

7° TYP.

PIN 2 & 4

.040 (1.02)

.060 (1.52)

.190 (4.83)

.210 (5.33)

.012 (.30)

.024 (.61)

.080 (2.03)

.120 (3.05)

.234 (5.94)

.261 (6.63)

.165 (4.19)

.185 (4.70)

.040 (1.02)

.060 (1.52)

.045 (1.14)

.055 (1.40)

.670 (17.02)

REF.

.570 (14.48)

REF.

TO-220-7C

TOP242-250

4/05

SMD-8B

PI-2546-121504

.004 (.10)

.012 (.30)

.036 (0.91)

.044 (1.12)

.004 (.10)

0 -

° 8°

.367 (9.32)

.387 (9.83)

.048 (1.22) .009 (.23)

.053 (1.35)

.032 (.81)

.037 (.94)

.125 (3.18)

.145 (3.68)

-D-

Notes:

1. Controlling dimensions are

inches. Millimeter sizes are

shown in parentheses.

2. Dimensions shown do not

include mold flash or other

protrusions. Mold flash or

protrusions shall not exceed

.006 (.15) on any side.

3. Pin locations start with Pin 1,

and continue counter-clock-

wise to Pin 8 when viewed

from the top. Pin 6 is omitted.

4. Minimum metal to metal

spacing at the package body

for the omitted lead location

is .137 inch (3.48 mm).

5. Lead width measured at

package body.

6. D and E are referenced

datums on the package

body.

.057 (1.45)

.068 (1.73)

(NOTE 5)

E S

.100 (2.54) (BSC)

.372 (9.45)

.240 (6.10) .388 (9.86)

.137 (3.48)

MINIMUM

.260 (6.60) .010 (.25)

-E-

Pin 1

D S .004 (.10)

⊕

G08B

.420

.046 .060 .060 .046

.080

Pin 1

.086

.186

.286

Solder Pad Dimensions

Notes:

1. Package dimensions conform to JEDEC specification

MS-001-AB (Issue B 7/85) for standard dual-in-line (DIP)

package with .300 inch row spacing.

2. Controlling dimensions are inches. Millimeter sizes are

shown in parentheses.

3. Dimensions shown do not include mold flash or other

protrusions. Mold flash or protrusions shall not exceed

.006 (.15) on any side.

4. Pin locations start with Pin 1, and continue counter-clock-

wise to Pin 8 when viewed from the top. The notch and/or

dimple are aids in locating Pin 1. Pin 6 is omitted.

5. Minimum metal to metal spacing at the package body for

the omitted lead location is .137 inch (3.48 mm).

6. Lead width measured at package body.

7. Lead spacing measured with the leads constrained to be

perpendicular to plane T.

.008 (.20)

.015 (.38)

.300 (7.62) BSC

(NOTE 7)

.300 (7.62)

.390 (9.91)

.367 (9.32)

.387 (9.83)

.240 (6.10)

.260 (6.60)

.125 (3.18)

.145 (3.68)

.057 (1.45)

.068 (1.73)

.120 (3.05)

.140 (3.56)

.015 (.38)

MINIMUM

.048 (1.22)

.053 (1.35)

.100 (2.54) BSC

.014 (.36)

.022 (.56)

-E-

Pin 1

SEATING

PLANE

-D-

-T-

P08B

DIP-8B

PI-2551-121504

D S .004 (.10)

⊕

T E D S .010 (.25) M

⊕

(NOTE 6)

.137 (3.48)

MINIMUM

TOP242-250

4/05

.165 (4.19)

.185 (4.70)

R07C

TO-263-7C

PI-2664-122004

-A-

LD #1

.580 (14.73)

.620 (15.75)

.390 (9.91)

.420 (10.67)

.326 (8.28)

.336 (8.53)

.055 (1.40)

.066 (1.68)

.100 (2.54)

REF

0.68 (1.73)

MIN

.208 (5.28)

Ref.

.024 (0.61)

.034 (0.86)

.225 (5.72)

MIN

.245 (6.22)

MIN

.000 (0.00)

.010 (0.25)

.090 (2.29)

.110 (2.79)

.012 (0.30)

.024 (0.61)

°8 -°0

.045 (1.14)

.055 (1.40)

.050 (1.27)

Notes:

1. Package Outline Exclusive of Mold Flash & Metal Burr.

2. Package Outline Inclusive of Plating Thickness.

3. Foot Length Measured at Intercept Point Between

Datum A Lead Surface.

4. Controlling Dimensions are in Inches. Millimeter

Dimensions are shown in Parentheses.

5. Minimum metal to metal spacing at the package body

for the omitted pin locations is .068 in. (1.73 mm).

.004 (0.10)

.315 (8.00)

.128 (3.25)

.038 (0.97)

.050 (1.27)

.380 (9.65)

.638 (16.21)

Solder Pad

Dimensions

TOP242-250

4/05

PI-2757-122004

Notes:

1. Controlling dimensions are inches. Millimeter

dimensions are shown in parentheses.

2. Pin numbers start with Pin 1, and continue

from left to right when viewed from the front.

3. Dimensions do not include mold flash or

other protrusions. Mold flash or protrusions

shall not exceed .006 (.15mm) on any side.

4. Minimum metal to metal spacing at the pack-

age body for omitted pin locations is .068

inch (1.73 mm).

5. Position of terminals to be measured at a

location .25 (6.35) below the package body.

6. All terminals are solder plated.

F07C

PIN 1 PIN 7

MOUNTING HOLE PATTERN

.050 (1.27)

.150 (3.81)

.050 (1.27)

.150 (3.81)

.050 (1.27)

.100 (2.54)

.180 (4.58)

.200 (5.08)

PIN 1 .010 (.25) M

.326 (8.28)

.336 (8.53)

.390 (9.91)

.420 (10.67)

.795 (20.18)

REF.

.024 (.61)

.034 (.86)

.050 (1.27) BSC

.150 (3.81) BSC

.055 (1.40)

.066 (1.68)

PIN 1 & 7

7° TYP.

PIN 2 & 4

.040 (1.06)

.060 (1.52)

.190 (4.83)

.210 (5.33)

.012 (.30)

.024 (.61)

.080 (2.03)

.120 (3.05)

.165 (4.17)

.185 (4.70)

.040 (1.02)

.060 (1.52)

.045 (1.14)

.055 (1.40)

.595 (15.10)

REF.

.495 (12.56)

REF.

TO-262-7C

.068 (1.73) MIN

TOP242-250

4/05

Revision Notes Date

D - 11/00

E 1) Added R package (D2PAK).

2) Corrected abbreviations (s = seconds).

3) Corrected x-axis units in Figure 11 (µA).

4) Added missing external current limit resistor in Figure 25 (RIL).

5) Corrected spelling.

6) Added caption for Table 4.

7) Corrected Breakdown Voltage parameter condition (TJ = 25 °C).

8) Corrected font sizes in ﬁgures.

9) Figure 40 replaced.

10) Corrected schematic component values in Figure 44.

7/01

F 1) Corrected Power Table value. 9/01

G 1) Added TOP250 device and F package (TO-262).

2) Added R package Thermal Impedance parameters and adjusted Output Power values in Table 1.

3) Adjusted Off-State Current value.

1/02

H 1) Added note to parameter table for Breakdown Voltage measurement.

2) Miscellaneous text corrections.

9/02

I 1) Updated P, Y, R and F package information.

2) Revised thermal impedances (θJA) for all package types.

3) Expanded Maximum Duty Cycle and deleted Maximum Duty Cycle Reduction Slope parameters.

4) Corrected DIP-8B and SMD-8B Package Drawings.

4/03

J 1) Added TOP245P.

2) Miscellaneous text corrections.

8/03

K 1) Corrected typographic errors in Figures 4, 6, 20, 28 and 34; and in MULTI-FUNCTION (M) Pin

Operation section.

9/03

L 1) Added TOP246P. 3/04

M 1) Added lead-free ordering information. 12/04

N 1) Updated Maximum Duty Cycle conditions.

2) Minor error corrections.

3) Added Note 4 to Absolute Maximum Ratings speciﬁcation.

4/05

TOP242-250

4/05

For the latest updates, visit our website: www.powerint.com

Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power Integrations does not assume

any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS MAKES NO WARRANTY HEREIN AND SPECIFICALLY

DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A

PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.

PATENT INFORMATION

The products and applications illustrated herein (including transformer construction and circuits external to the products) may be covered by one or more U.S.

and foreign patents, or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A complete list of Power Integrationsʼ patents

may be found at www.powerint.com. Power Integrations grants its customers a license under certain patent rights as set forth at http://www.powerint.com/ip.htm.

LIFE SUPPORT POLICY

POWER INTEGRATIONSʼ PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS

WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF POWER INTEGRATIONS. As used herein:

1. A Life support device or system is one which, (i) is intended for surgical implant into the body, or (ii) supports or sustains life, and (iii) whose failure to perform,

when properly used in accordance with instructions for use, can be reasonably expected to result in signiﬁcant injury or death to the user.

2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life

support device or system, or to affect its safety or effectiveness.

The PI logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, EcoSmart, PI Expert and PI FACTS are trademarks of

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