ILC6377SOADJ - Fairchild Semiconductor Corporation

www.fairchildsemi.com

Rev. 1.5 November 2001

Features

• ±2.5% accurate output voltages

• Guar a nt ee d 500mA output curr e nt

• 95% efficiency

• 55µA no load battery input current (ILC6377)

• 1.5µA shutdown current

• Built in short circuit and overcurrent protection

• Undervoltage lockout and soft-start

• External transistor drive available for higher IOUT

• 300kHz op eration

• Automatic switchover to PFM mode at low currents for

longest battery life (ILC6377)

• Fixed 3.3V or 5V or adjustable output

•SO-8 package

Applications

• Cellular Phones

• Palmtops and PDAs

• Portable Instrumentation

• Buck Converter for Industrial / Networking Applications

Description

The ILC6376/77 is a 95% efficient, 300kHz step-down DC-

DC converter in an SO-8 package; capable of delivering

500mA out p ut cur rent . The devi ce is also capa ble of d riving

an external FET for higher output current applications.

The ILC6376/77 uses a unique p-channel architecture with

built-in charge pump to maintain low on-resistance, even at

low input voltages. The ILC6376 operates in PWM mode

with 30 0kH z s wit c h i ng frequency. The ILC6377 doe s t he

same at high and medium load currents. When the load

curre nt dro ps and t he d evi c e hits appr oximate ly 25 % dut y

cycle, ILC6377 automatically switches over to PFM or pulse

skipp i ng mode. PFM (pul se freque nc y modu lation) mode of

operation extends efficiency at light loads.

Start-up is controlled via an external soft-start capacitor. The

device will automatically re-enter start-up mode when an

output current overload condition is sensed; thus providing

automatic short-circuit protection. Voltage lockout prevents

faulty operation below the minimum operating voltage level.

In shutdo wn, the ILC6376/7 7 cons umes only 1.5µA current.

The ILC6376/77SOXX offers fixed 3.3V or 5V output while

ILC6376/77SOADJ allows adjustable output. Both versions

of ILC6376/77 are available in an SO-8 surface mount

package.

Typi cal Appl ica t ions

VOUT

ILC6376/77

(TOP VIEW)

+CL

VIN

S/D

CSS

SD1

*CIN

Fig 1. Typical step-down DC-DC

converter application

22µH

47µF

10µF

ILC6376/77

0.5A, 300kHz, SO-8 PWM/PFM Step Down Converter with

Shutdown

SD1: SS12 Sc hottky Dio de (FAIRCH ILD)

CL: 10V/47µF Tantalum Capacitor (NICHICON, F93)

CSS: 4700pF Ceramic Capacitor

CIN: 16V / 10µF Tantalum Capacitor (NICHIC ON , F93)

Pin Assignments

Pin Definitions

Internal Block Dia gr a m

Pin Symbol Function

IN Power Supply

2 EXT2 External gate drive pin (low when P-Ch FET is ON)

3 P-BST P-Ch gate boost

4 S/D,

Softstart, VREF

Shutdown, also soft-start capacitor pin and VREFoutput

OUT / FB Output voltage sense pin for ILC6376/77SO-XX; 1V feedback pin for

ILC6376/77SO-ADJ

6 GND Ground connection

7 EXT1 External gate drive pin (low when P-Ch FET is ON)

XInductor Switch Pin

ILC6376/77

(TOP VIEW)

8LX

EXT

S/D, GND

P_BST

EXT2

VIN

CSS

ILC6376/77 SOXX

SO-8 Package

ILC6376/77

(TOP VIEW)

VOUT

EXT1

S/D,

GND

P_BST

EXT2

VIN

CSS

ILC6376/77 SOADJ

SO-8 Package

PWM/PFM

Protection

GND

EXT1

RAMP WAVE

VIN

VOUT

P_BST

GATE

DRIVER

GENERATOR,

OSCILLATORCONTROLLER

PWM

Comp EXT2

Error

Amp

S/D,

Softstart,

Vref S/D,

Vref

with

Soft-

start

ILC6376/77

Absolute Maxim um Ratings (TA=25°C)

Electrical Characteristics ILC6376/77SO33

VOUT = 3.3V, VIN = 4V, FOSC=300kHz, IOUT = 130mA, TA = 25°C, unl ess ot he r wi se sp ec i fie d . Cir cui t confi g uration figure 1 .

Parameter Symbol Ratings Units

VIN Input Voltage Pin VIN -0.3 to +12 V

VOUT Pin (ILC6376/77SOXX)

FB Pin (ILC6376/77SOADJ) VOUT

VFB

-0.3 to +12

-0.3 to VIN +0.3 V

Voltage on LX pin VLX VIN - VLX = -0.3 to +12 V

Peak Switch Current on LX pin ILX 700 mA

Voltage on P_BST pin VDP_BST VIN - VP_BST = -0.3 to +12 V

Current EXT1, EXT2 pins IEXT1, IEXT2±50 mA

Voltage on all other pins ~ -0.3 to VIN + 0.3 V

Continuous Total Power Dissipation PD300 mW

Operating Ambient Temperature TOPR -30~+80 °C

Storage Temperature TSTG -40~+125 °C

Parameter Symbol Conditions Min. Typ. Max. Units

Output Voltage VOUT 3.218 3.300 3.383 V

Input Voltage VIN 10 V

Output Maximum Current IOUT(MAX) 500 600 mA

Input Current Supply IIN VIN 3.5V, No Loads ILC6376 1480 2190 µA

ILC6377 50 86

Shutdown Current IS/D VS/D = 0V 1.5 2.5 µA

LX Switch On - Resistance Rds(on) Open Loop Measurement, VS/D =

VIN, VLX = VIN - 0.2V, VOUT = 3V 0.64 0.85 Ω

LX Switch Leakage Current ILXL Open Loop Measurement, VOUT =

VIN, VLX = 0V 2.0 µA

Oscillator Frequency FOSC Measurement Waveform at EXT pin

VIN = 3.6V IOUT = 20mA 255 300 345 kHz

Max Duty Cycle MAXDTY 100 %

PFM Duty Cycle PFMDTY No Load (ILC6377) 15 25 35 %

Efficiency EFFI 95 %

Undervoltage Lockout VUVLO Minimum VIN when Vref does not

start up 0.9 1.8 V

Soft-Start Time TSS VREF rises to 0V from 0.9V 6.0 10.0 16.0 msec

Shutdown Input Voltage VSD High = Regulator “ON”

Low = Regulator “OFF” 0.65 0.2 V

EXT1, EXT2 Hi On-

Resistance REXtHI 3V applied to VOUT with no external

components 35 47 Ω

EXT1, EXT2 Low On-

Resistance REXtLOW 3.6V applied to VOUT with no

external components 29 37 Ω

ILC6376/77

Parameter Symbol Conditions Min. Typ. Max. Units

Output Voltage VOUT 4.875 5.000 5.125 V

Input Voltage VIN 10 V

Output Maximum Current IOUT(MAX) 500 600 mA

Input Supply Current IIN VIN 5.25V, No Load ILC6376 2540 3740 µA

ILC6377 71 110

Shutdown Current IS/D VS/D = 0V 1.5 2.5 µA

LX Switch On-Resistance Rds(on) Open Loop Measurement, VS/D = V IN,

VLX =VIN - 0.2V, VOUT = 4.5V 0.44 0.58 Ω

LX Switch Leakage Current ILXL Open Loop Measurement, VOUT =

VIN, VLX = 0V 2.0 µA

Oscillator Frequency FOSC Measure Waveform at EXT pin VIN =

5.3V

IOUT = 20mA

255 300 345 kHz

Max Duty Cycle MAXDTY 100 %

PFM Duty Cycle PFMDTY No Load (ILC6377) 15 25 35 %

Efficiency EFFI 95 %

Undervoltage Lockout VUVLO Minimum VIN when VREF does not

start up 0.9 1.8 V

Soft-Start Time TSS VREF rises to 0V from 0.9V 6.0 10.0 16 msec

Shutdown Input Voltage VS/D High = Regulator “ON”

Low = Regulator “OFF” 0.65 0.2 V

EXT1, EXT2 Hi On-

Resistance REXtHI Open Loop Measurement 24 32 Ω

EXT1, EXT2 Low On-

Resistance REXtLOW Open Loop Measurement 20 26 Ω

Electrical Characteristics ILC6376/77SO50

Unless Otherwise specified all limits are at VOUT = 5.0V, VIN = 6V, FOSC=300kHz, IOUT = 200mA, TA = 25°C. Circuit config-

uration figure 1.

ILC6376/77

Electrical Characteristics ILC6376/77SOADJ

Unless Otherwise specified all limits are at VOUT program me d to 5.0V, VIN = 6V, FOSC=300kHz, IOUT = 200mA, TA = 25°C.

Circuit configuration figure 1.

Parameter Symbol Conditions Min. Typ. Max. Units

Feedback Voltage (pin 5) VFB .995 1.000 1.015 V

Output Voltage VOUT RFB1 + RFB2 < 2MΩ1.5 6 V

Output Maximum Current IOUT(MAX) 500 600 mA

Input Supply Current IIN VIN 5.25V, No Load 71 110 µA

Shutdown Current IS/D VS/D = 0V 1.5 2.5 µA

LX Switch On-Resistance Rds(on) Open Loop Measurement, VS/D = VIN,

VLX = VIN - 0.2V, VOUT = 4.5V 0.44 0.58 Ω

LX Leak Current ILXL Open Loop Measurement, VOUT =

VIN, VLX = 0V 2.0 µA

Oscillator Frequency FOSC Measure Waveform at EXT pin VIN =

5.3V IOUT = 20mA 255 300 345 kHz

Max Duty Cycle MAXDTY 100 %

PFM Duty Cycle PFMDTY No Load (ILC6377) 15 25 35 %

Efficiency EFFI 95 %

Undervoltage Lockout VUVLO Minimum VIN when VREF does not

start up 0.9 1.8 V

Soft-Start Time TSS VREF rises to 0V from 0.9V 6.0 10.0 16.0 msec

Shutdown Input Voltage VS/D High = Regulator “ON”

Low = Regulator “OFF” 0.65 0.2 V

EXT1, EXT2 Hi On-

Resistance REXtHI Open Loop Measurement 24 32 Ω

EXT1, EXT2 Low On-

Resistance REXtLOW Open Loop Measurement 20 26 Ω

ILC6376/77

External component selection

Proper selection of external components is important for

achieving high performance. The outpu t inductor selected

should have low DC resistance on the order of 0.2Ω or less

and sa t uration current r a t i ng of 1A or higher. Recommended

inductors are Sumida CD54 (22µH, 0.18Ω max DC resis-

tance) or Co il cra f t DO330 8P - 22 3 (22µH, 0.18Ω max DC

resis tan ce ) or equ i val e nt.

The catch diode should be a schottky diode with low forward

drop a nd rate d at 1A or gre a t er c urrent , SS 12 or i t ’s equi va-

lent is recomme nded.

Input and output capacitors should be tantalum capacitors

with low equivalent series resistance (ESR) and voltage rat-

ing higher than the actual application.

Soft-start

Pin 4 of I LC637 6/77 f uncti ons as the so ft-st art pin as we ll as

the shutdown pin. A soft-start capacitor (from pin 4 to

ground) controls the rate at which the power supply starts up;

thus preventing large overshoots at the output as well as

large in-rush current. The value for CSS should be 100pF or

greater.

Shutdown

The ILC6376/77 is placed in shutdown mode by taking pin 4

to gr ound. In shutdow n, the quies cent cur rent o f the d evice i s

under 2µA. When usi ng the shu tdown fe atu re , pin 4 must be

driven from an ope n colle c t or o r ope n drai n output without

employing an external pull-up resistor, as shown in figure 2.

Over-current and short-circuit protection

In the event of an over-current or short-circuit condition, the

ILC6376/77 cycles the soft-start pin in a hiccup mode to pro-

vide fa ul t protec tion . When the out put vo lta ge dec re ases due

to ov e r lo ad, the I LC6376/77 will operate continuously at the

maximum duty cycle. If the period of maximum duty cycle

operation exceeds TPRO (typically 5 msec) , pin 4 will be

pulled low; thus discharging the external soft-start capacitor

CSS. This action inhibits the regulator’s PWM action. Next,

the ILC6376/77’s soft-start cir cuitry starts recharging CSS

and initiates a controlled start-up. If the overload condition

continues to exist, the above sequence of events will repeat;

thus continuing to cycle the soft-start function.

Note that very little power is dissipated with this method of

fault protection versus constant current limit protection.

Even though the internal power MOSFET is pulsed on and

off at high peak current, the DC current is low; thus leading

to low power dissipation even under short-circuit conditions.

Keep in mind that the duration of maximum duty cycle

condition is used to trigger the ILC6376/77’ s fault protec-

tion circuit. As such, a small input-output (VIN - VOUT)

differential voltage may trigger the device’s fault protec-

tion circuitry eve n at low output curr ent.

Undervoltage Lockout

The undervoltage lockout feature prevents faulty operation

by disabling the operation of the regulator when input volt-

age is below the minimum operating voltage, VUVLO.

When the input voltage is lower than VUVLO the device

disables the internal P-channel MOSFET and provides

“high” output at both EXT1 and EXT2 outputs.

VOUT

ILC6376/77

(TOP VIEW)

+CL

VIN

S/D

CSS

SD1

*CIN

Fig 1. Typical step-down DC-DC

converter application

SD1: SS12 Schottky Dio de (FAIRCHILD)

CL: 10V/47µF Tantalum Capacitor (NICHIC ON, F93)

CSS: 4700pF Ceramic Capacitor

CIN: 16 V / 10µF Tantalum Capacitor (NICHICON, F93)

22µH

47µF

10µF

Figur e 1 shows a t ypical fixed output voltage step- down DC-DC

conv erter application circu it for ILC6376/77 SOXX.

ILC6376/77

1kHz < < 20kHz

The EXT1 and EXT2 pins are provided so as to drive exter-

nal transistors; thus allowing design flexibility. The EXT1

output drive signal has the same timing as the gate drive to

the internal P-channel MOSFET i.e. EXT1 output is lo w as

long as the internal MOSFET is on. Both EXT1 and EXT 2

pins are capable of driving 1000pF gate capacitance. For

example, a high output current application circuit using an

external P-channel MOSFET is shown in figure 2.

P-Channel Boost Circuit

The ILC6376/77 inclu des a un ique P-Ch a nn el MOSFET

architecture with built-in charg e pump to maintain low on-

resis tance eve n at low input voltage s. As show n in fi gure 3, a

2200pF cer amic cap acito r and a scho ttky diod e ( MBR05 20L

or equivalent) allows the gate voltage of the internal P-Chan-

nel MOSFET to be driven negative; thus reducing the switch

on-resistance. This technique can be employed to increase

efficiency at low input voltages and high output currents.

Note that the voltage between VIN and P_BST should not

exceed 10V, otherwise damage to the device may occur. For

high input voltage applications the schottky diode should be

replaced by a low voltage zener diode so that the P_BST pin

is clamped to a safe negative voltage.

Adjustable Output (ILC6376/77SOADJ)

For adjustable output voltage ILC6376/77SOADJ should be

used. All connections to the ILC6376/77SOADJ are the

same as IL C6376/77SOXX, except for the feedback voltage

divider network shown in figure 4. The output voltage,

VOUT, can be calculated from the following equation:

VOUT = VFB (1 + RFB1/RFB2 ), where V FB is approximately

1V and RFB1 + RFB2 < 2MΩ

The feedback compensation capacitor should be chosen such

that the pole frequency f is between 1kHz and 20kHz:

The pole frequency should generally be set at 5kHz. The

value of CFB calculated from the above equation may require

some adjustment depending on the output inductor (L) and

output capacitor (CL) values chosen.

Example for 3V output:

RFB1 = 400kΩ

RFB2 = 200kΩ

CFB = 100pF

PC Board Layout

As with all switching DC-DC converter designs, good PC

board layout is critical for optimum performance. The heavy

lines indicated in figure 1 schematic should be wide

printed circuit board traces and should be kept as short

as is practical. A large ground plane with as much copper

area as is allowable should be used. All external components

should be mounted as close to the IC as possible. For

ILC6376/77SOADJ, the feedback resistors and their associ-

ated wiring should be kept away from the inductor location

and the vicinity of inductive flux.

VOUT

ILC6376/77

(TOP VIEW)

+CL

VIN

S/D

CSS

SD1

*CIN

EXT1

Fig.2 1Amp output current application

using external MOSFET

VOUT

6CFB RFB1

RFB2

RFB1 + RFB2 < 2MW

chosen so that

To pi n 8

(Note: rest of circuit is same as Fig.1)

2 x π x CFB x RFB1

1kHz < 1< 20kHz

Fig.4 Adjustable output using ILC6376/77SOA

Figure 3. P-Chan nel Negative

CBST

Voltage between Vin and

P_BST must be less tha n 10V.

ILC6376/77

(TOP VIEW)

SD2

Boost Circuit

2200pF

Schottky

MBR0520L 2 x π x CFB x RFB1

Typical Performance Characteri s t ics

General conditions for all curves: Circuit 1; L = 20µH (Sumida, CD54), CIN = 47µF (tantalum) with 0.1µF (ceramic),

CL = 47µH (tantalum) SS12 schottky diode, CSS = 4700pF (ceramic), TA = 25°C unless otherwise noted.

OUTPUT CURRENT: I

OUT

(mA)

Output Voltage vs. Output Current

3.5

3.4

3.3

3.2

3.1

3.00.1 110

100 100

ILC6377SO33

OUTPUT VOLTAGE: V

OUT

(V)

L = 22µH (CD54

)

VIN = 3.96 5.0V

8.0V

Output Voltage vs. Output Current

5.4

5.2

5.0

4.8

4.6

4.4 0.1 110

100 100

ILC6377SO50

OUTPUT VOLTAGE: VOUT(V)

OUTPUT CURRENT: I

OUT

(mA)

L = 22µH (CD5

10.0V 6.0V

8.0V

Output Voltage vs. Output Current

3.5

3.4

3.3

3.2

3.1

3.0 0.1 110

100 100

ILC6377SO33

OUTPUT VOLTAGE: V

OUT

(V)

OUTPUT CURRENT: I

OUT

(mA)

L = 10µH (CD54

)

VIN = 3.96 5.0V

8.0V

Output Voltage vs. Output Current

3.5

3.4

3.3

3.2

3.1

3.0 0.1 110

100 100

ILC6376SO33

OUTPUT VOLTAGE: V

OUT

(V)

OUTPUT CURRENT: I

OUT

(mA)

L = 22µH (CD5

= 3.96V, 5.0V,8.0V

10.0V

Output Voltage vs. Output Current

3.5

3.4

3.3

3.2

3.1

3.0 0.1 110

100 100

ILC6377SO-33

OUTPUT VOLTAGE: V

OUT

(V)

OUTPUT CURRENT: I

OUT

(mA)

L = 47µH (CD105

)

= 4.0V 5.0V

8.0V

Output Voltage vs. Output Current

5.4

5.2

5.0

4.8

4.6

4.4 0.1 110

100 100

ILC6376SO50

OUTPUT VOLTAGE: VOUT(V)

OUTPUT CURRENT: I

OUT

(mA)

L =22µH (CD5

10.0V

6.0V 8.0V

ILC6376/77

Typical Performance Characteri s t ics

General conditions for all curves: Circuit 1; L = 20µH (Sumida, CD54), CIN = 47µF (tantalum) with 0.1µF (ceramic),

CL = 47µH (tantalum) SS12 schottky diode, CSS = 4700pF (ceramic), TA = 25°C unless otherwise noted.

Efficiency vs. Output Current

100

00.1 110

100 100

ILC6377SO33

EFFICIENCY: EFFI(%)

OUTPUT CURRENT: I

OUT

(mA)

L = 22µH (CD5

= 4.0V

5.0V

8.0V

Efficiency vs. Output Current

100

00.1 110

100 100

ILC6377SO33

EFFICIENCY: EFFI(%)

OUTPUT CURRENT: I

OUT

(mA)

L = 10µH (CD5

VIN = 3.96V

5.0V

8.0V

Efficiency vs. Output Current

100

00.1 110

100 100

ILC6377SO33

EFFICIENCY: EFFI(%)

OUTPUT CURRENT: I

OUT

(mA)

L = 47µH (CD105

)

= 4.0V 5.0V 8.0V

Efficiency vs. Output Current

100

00.1 110

100 100

ILC6376SO33

EFFICIENCY: EFFI(%)

OUTPUT CURRENT: IOUT(mA)

L = 22µH (CD5

VIN = 4.0V

5.0V

10.0V

8.0V

Efficiency vs. Output Current

100

00.1 110

100 100

ILC6376SO50

EFFICIENCY: EFFI(%)

OUTPUT CURRENT: IOUT(mA)

L = 22µH (CD5

VIN = 3.96V 10.0V

8.0V

5.0V

Efficiency vs. Output Current

100

00.1 110

100 100

ILC6377SO50

EFFICIENCY: EFFI(%)

OUTPUT CURRENT: I

OUT

(mA)

L = 22µH (CD5

= 6.0V 10.0

8.0V

ILC6376/77

Typical Performance Characteri s t ics

General conditions for all curves: Circuit 1; L = 20µH (Sumida, CD54), CIN = 47µF (tantalum) with 0.1µF (ceramic),

CL = 47µH (tantalum) SS12 schottky diode, CSS = 4700pF (ceramic), TA = 25°C unless otherwise noted.

-40 -20 0 20 40 60 8

ILC6377SO33

Output Voltage vs.

Ambient Temperature

STAND-BY CURRENT (µA)

AMBIENT TEMP.: T

(˚C)

3.40

3.35

3.20

3.25

3.30

400

350

300

250

200

-40 -20 0 20 40 60 8

ILC6377SO33

Oscillation Frequency vs.

Ambient Temperature

OSCILLATION FREQUENCY: F

OSC

(kHz)

AMBIENT TEMP.: T

(˚C)

100

-40 -20 0 20 40 60 80

ILC6377SO33

Stand-by Current vs. Ambient Temperatu

SUPPLY CURRENT: I

(µA)

AMBIENT TEMP.: T

(˚C)

1.2

-40 -20 0 20 40 60 80

ILC6377SO33

On Resistance vs. Ambient Temperatur

SWITCH RESISTANCE: R

DS(ON)

(Ω)

AMBIENT TEMP.: T

(˚C)

1.0

0.8

0.6

0.4

0.2

-40 -20 0 20 40 60 8

ILC6377SO33

PFM Duty Ration vs.

Ambient Temperature

PFM DUTY RATIO: PFMDTY(%)

AMBIENT TEMP.: TA (˚C)

3.40

3.35

3.20

3.25

3.30

3.40

3.35

3.30

3.26

3.20

-40 -20 0 20 40 60 8

ILC6377SO33

Output vs. Ambient Temperature

OUTPUT VOLTAGE (V)

AMBIENT TEMP.: TA (˚C)

ILC6376/77

Typical Performance Characteri s t ics

General conditions for all curves: Circuit 1; L = 20µH (Sumida, CD54), CIN = 47µF (tantalum) with 0.1µF (ceramic),

CL = 47µH (tantalum) SS12 schottky diode, CSS = 4700pF (ceramic), TA = 25°C unless otherwise noted.

-40 -20 0 20 40 60 8

ILC6377SO33

Soft-Start Time vs. Ambient Temperatu

SOFT-START TIME: TSS(ms)

AMBIENT TEMP.: TA (˚C)

-40 -20 0 20 40 60 8

ILC6377SO33

CE "H" Voltage vs. Ambient Temperatu

CE "H" VOLTAGE: V

CEL

(V)

AMBIENT TEMP.: T

(˚C)

0.8

0.6

0.4

0.2

1.0

-40 -20 0 20 40 60 8

ILC6377SO33

Minimum Operating Voltage vs.

Ambient Temperature

MIN. OPERATING VOLTAGE: V

OUT

(V)

AMBIENT TEMP.: T

(˚C)

1.6

1.4

1.2

1.0

0.8

1.8

-40 -20 0 20 40 60 8

ILC6377SO33

CE "L" Voltage vs.

Ambient Temperature

CE "L" VOLTAGE: VCEL(V)

AMBIENT TEMP.: TA (˚C)

0.8

0.6

0.4

0.2

0.8

1.0

100

-40 -20 0 20 40 60 8

ILC6377SO33

Efficiency vs. Ambient Temperature

EFFICIENCY: EFFI(%)

AMBIENT TEMP.: T

(˚C)

ILC6376/77

11/21/01 0.0m 001

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Ordering Information

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ILC6376ADJ Adjustable, 300kHz step-down PWM converter

ILC6377SO33 3.3V, 300kHz step-down PWM/PFM converter

ILC6377SO50 5V, 300kHz step-down PWM/PFM converter

ILC6377SOADJ Adjustable, 300kHz step-down PWM/PFM converter

ILC6376/77

Product Folder - Fairchild P/N ILC6376SO50 - Product information

Fairchild Semiconductor

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Contents

General description | Features | Applications |

Product status/pricing/packaging

General description

The ILC6376/77 is a 95% efficient, 300kHz

step-down DCDC converter in an SO-8

package; capable of delivering 500mA output

current. The device is also capable of driving

an external FET for higher output current

applications.

The ILC6376/77 uses a unique p-channel

architecture with built-in charge pump to

maintain low on-resistance, even at low input

voltages. The ILC6376 operates in PWM mode

with 300kHz switching frequency. The

ILC6377 does the same at high and medium

load currents. When the load current drops and

the device hits approximately 25% duty cycle,

ILC6377 automatically switches over to PFM

or pulse skipping mode. PFM (pulse frequency

modulation) mode of operation extends

efficiency at light loads.

Start-up is controlled via an external soft-start

capacitor. The device will automatically re-

enter start-up mode when an output current

overload condition is sensed; thus providing

automatic short-circuit protection. Voltage

lockout prevents faulty operation below the

minimum operating voltage level. In shutdown,

the ILC6376/77 consumes only 1.5µA current.

The ILC6376/77SOXX offers fixed 3.3V or

5V output while ILC6376/77SOADJ allows

adjustable output. Both versions of

ILC6376/77 are available in an SO-8 surface

mount package.

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Datasheet

Download this

datasheet

PDF

e-mail this datasheet

[E-

mail]

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Product Folder - Fairchild P/N ILC6376SO50 - Product information

Features

● ±2.5% accurate output voltages

● Guaranteed 500mA output current

● 95% efficiency

● 55µA no load battery input current

● 1.5µA shutdown current

● Built in short circuit and overcurrent

protection

● Undervoltage lockout and soft-start

● External transistor drive available for

higher IOUT

● 300kHz operation

● Automatic switchover to PFM mode at

low currents for longest battery life

(ILC6377)

● Fixed 3.3V or 5V or adjustable output

● SO-8 package

Applications

● Cellular Phones

● Palmtops and PDAs

● Portable Instrumentation

● Buck Converter for Industrial /

Networking Applications

Product status/pricing/packaging

Product Product status Package type Leads Package marking Packing

method

ILC6376SO50 Not recommended for new

designs SOIC 8 $Y&Z&2&T RAIL

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Product Folder - Fairchild P/N ILC6377SOADJ - Product information

Fairchild Semiconductor

space

SEARCH | Parametric | Cross Reference

space

Product Folders and

Datasheets

Application

notes

space

find products

Home >> Find products >>

space

Products groups

space

Analog and Mixed

Signal

Discrete

Interface

Logic

Microcontrollers

Non-Volatile

Memory

Optoelectronics

Markets and

applications

New products

Product selection and

parametric search

Cross-reference

technical information

buy products

technical support

my Fairchild

company

ILC6377SOADJ

Product information Related Links

Request samples

Dotted line

How to order products

Dotted line

Product Change Notices

(PCNs)

Dotted line

Support

Dotted line

Distributor and field sales

representatives

Dotted line

Quality and reliability

Dotted line

Design tools

Contents

General description | Features | Applications |

Product status/pricing/packaging

General description

The ILC6376/77 is a 95% efficient, 300kHz

step-down DCDC converter in an SO-8

package; capable of delivering 500mA output

current. The device is also capable of driving

an external FET for higher output current

applications.

The ILC6376/77 uses a unique p-channel

architecture with built-in charge pump to

maintain low on-resistance, even at low input

voltages. The ILC6376 operates in PWM mode

with 300kHz switching frequency. The

ILC6377 does the same at high and medium

load currents. When the load current drops and

the device hits approximately 25% duty cycle,

ILC6377 automatically switches over to PFM

or pulse skipping mode. PFM (pulse frequency

modulation) mode of operation extends

efficiency at light loads.

Start-up is controlled via an external soft-start

capacitor. The device will automatically re-

enter start-up mode when an output current

overload condition is sensed; thus providing

automatic short-circuit protection. Voltage

lockout prevents faulty operation below the

minimum operating voltage level. In shutdown,

the ILC6376/77 consumes only 1.5µA current.

The ILC6376/77SOXX offers fixed 3.3V or

5V output while ILC6376/77SOADJ allows

adjustable output. Both versions of

ILC6376/77 are available in an SO-8 surface

mount package.

space

Datasheet

Download this

datasheet

PDF

e-mail this datasheet

[E-

mail]

This pagePrint version

file:///D|/HTML/ILC6377SOADJ.html (1 of 3) [7/26/02 5:11:56 PM]

Product Folder - Fairchild P/N ILC6377SOADJ - Product information

Features

● ±2.5% accurate output voltages

● Guaranteed 500mA output current

● 95% efficiency

● 55µA no load battery input current

● 1.5µA shutdown current

● Built in short circuit and overcurrent

protection

● Undervoltage lockout and soft-start

● External transistor drive available for

higher IOUT

● 300kHz operation

● Automatic switchover to PFM mode at

low currents for longest battery life

(ILC6377)

● Fixed 3.3V or 5V or adjustable output

● SO-8 package

Applications

● Cellular Phones

● Palmtops and PDAs

● Portable Instrumentation

● Buck Converter for Industrial /

Networking Applications

Product status/pricing/packaging

Product Product status Pricing* Package type Leads Package marking Packing

method

ILC6377SOADJX Full Production $3.24 SOIC 8 $Y&Z&2&T TAPE REEL

* 1,000 piece Budgetary Pricing

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