Sanken Power Devices
from Allegro MicroSystems
All performance characteristics given are typical values for circuit or
system baseline design only and are at the nominal operating voltage and
.detats esiw re hto sselnu ,C°52+ fo erutarepmet tneibma na
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
STR-A6252M
67 kHz PWM with ±5% frequency jittering for EMI noise
filtering and cost reduction
Rugged 650 V avalanche-rated MOSFET:
• Simplified surge absorption
• No VDSS derating required
Low RDS(on) : 2.8 Ω maximum
Auto-burst mode for stand-by operation or light loads; less
transformer audible noise
Built-in leading edge blanking
Soft start and low start-up current; start-up circuit disabled in
operation
Auto-burst stand-by (intermittent operation) input power
<0.1 W at no load
Built-in constant-voltage/constant current (CV/CC)
Multiple protections:
• Pulse-by-pulse overcurrent protection (OCP)
• Overload protection (OLP) with auto restart
• Latching overvoltage protection (OVP)
• Undervoltage lockout (UVLO) with hysteresis
• Latching thermal shutdown (TSD)
FEATURES AND BENEFITS
STR-A6252M
The STR-A6252M is a 67 kHz PWM topology (with ±5%
frequency jittering for minimum EMI) regulator specifically
designed to satisfy the requirements for increased integration and
reliability in flyback converters. It incorporates a primary control
and drive circuit with an avalanche-rated power MOSFET. This
is a higher-frequency version of the STR-A6252.
Covering the power range from below 24 watts for a
230 VAC input, or to 20 watts for a universal (85 to 264 VAC)
input, this device can be used in a wide range of applications,
from DVD players and VCR player/recorders to ac adapters
for cellular phones and digital cameras. An auto-burst standby
function reduces power consumption at light load, while multiple
protections, including the avalanche-energy guaranteed MOSFET,
provide high reliability of system design.
Cycle-by-cycle current limiting, undervoltage lockout with
hysteresis, overvoltage protection, and thermal shutdown protect
the power supply during the normal overload and fault conditions.
Overvoltage protection and thermal shutdown are latched after a
short delay. The latch may be reset by cycling the input supply.
Low start-up current and a low-power standby mode selected
from the secondary circuit completes a comprehensive suite of
features.
It is provided in an 8-pin mini-DIP plastic package with pin
6 removed. The leadframe plating is pure Sb, and the package
complies with RoHS.
Always order by complete part number, e.g.:
Approximate Scale 1:1
Package DIP-8
Switching
Regulators
Datasheet 28103.44-5a
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
2
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
FUNCTIONAL BLOCK DIAGRAM AND TERMINAL ASSIGNMENTS
Drive
8
1
5
D
Vcc
2
LEB
S/OCP
TSD
PWM OSC
Internal
BIAS
FM/SS
32V
3
GND
FB/CC
/OLP
4
R
SQ
OCP
CV/CC
Istartup
=1.1mA
Frequency
Modulation
Soft Start
UVLO
RESET
OLP
125°C
OVP
Feedback
Control
R
S
Q
Delay
7.2V
10 µs
13.4V/10V
7
D
Number Name Description Functions
1 S/OCP Source/OCP terminal MOSFET Source/Overcurrent
protection
2 FM/SS FM/Soft start terminal Capacitor connection terminal for
frequency jitter and soft start.
3 GND Ground terminal Ground
4 FB /CC/OLP FB/CC/OLP terminal
Input of constant voltage control
signal / constant current operation
control signal / over load protection
signal
5 VCC Power supply terminal Input of power supply for control
circuit
7D Drain terminals MOSFET drain / Input of startup
current
8
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
3
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
ABSOLUTE MAXIMUM RATINGS at TA = 25°C
Characteristic Symbol Terminal Note Max. Unit
Drain Current1IDpeak 8-1 Single Pulse 3.0 A
Maximum Switching Current IDMAX 8-1 VS/OCP = 0.81 V with reference to GND,
TA = –20 to 125°C 3.0 A
Single Pulse Avalanche Energy2EAS 8-1 Single Pulse 123 mJ
VDD = 99 V, L = 20 mH, IL = 3.0 A 123 mJ
S/OCP Terminal Voltage VOCP 1-3 –0.3 to 6 V
Controller (MIC) Input Voltage Vcc 5-3 36 V
FB/CC/OLP Terminal Voltage VFB 4-3 –0.3 to 12 V
FM Terminal Voltage VFM 2-3 –0.3 to 6 V
MOSFET Power Dissipation3,4 PD1 8-1 1.35 W
Controller (MIC) Power Dissipation5PD2 5-3 For Vcc×Icc 0.15 W
Operating Internal Frame Temperature6TFRefer to TOP –20 to 125 °C
Operating Ambient Temperature Top –20 to 125 °C
Storage Temperature Tstg –40 to 125 °C
Channel Junction Temperature TJ150 °C
1Refer to figure 1
2Refer to figure 3
3Refer to figure 5
4Mounted on 15 x 15 mm printed circuit board
5Refer to figure 6
6Measured at the root of terminal 3
Temperature, T
F
(°C)
Safe Operating Area
Temperature Derating Coefficient (%)
0
20
40
60
80
100
0 25 50 75 100 125 150
Drain-to-Source Voltage, VDS (V)
Drain Current, ID (A)
1.00
0.10
0.01
10.00
10 100 10001
1 ms
0.1 ms
Current limit
due to R
DS(on)
Refer to figure 1 for MOSFET SOA
temperature derating coefficient
Figure 1 – MOSFET Safe Operating Area
Derating Curve Figure 2 – MOSFET Safe Operating Area
Drain Current versus Voltage
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
4
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Channel Junction Temperature, T
J
(°C)
E
AS
Derating Coefficient (%)
0
20
40
60
80
100
25 50 75 100 125 150
t(s)
Transient Thermal Resistance, RθJC (°C/W)
1.00
0.10
0.01
10.00
100µ10µ 10m1m 100m1µ
Ambient Temperature, TA (°C)
Power Dissipation, PD1 (W)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 20 40 60 80 100 120 140 160
P
D1
= 1.35 W at T
A
&
Internal Frame Temperature, TF (°C)
Power Dissipation, PD2 (W)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 20 40 60 80 100 120 140 160
P
D2
= 0.15 W at T
A
&
Figure 6 – MIC Power Dissipation versus Temperature
Figure 3 – MOSFET Avalanche Energy Derating Curve Figure 4 – Transient Thermal Resistance
Figure 5 – MOSFET Power Dissipation versus Temperature
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
5
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
ELECTRICAL CHARACTERISTICS for Controller (MIC), valid at TA = 25°C, VCC = 18 V, unless otherwise specified
Characteristic Symbol Terminal Test Conditions Min. Typ. Max. Unit
Operation Start Voltage VCC(ON) 5-3 (Power supply voltage at which device starts operating)
Measurement circuit 1, VCC = 0 through 12.9 to 15.7 V 12.9 14.3 15.7 V
Operation Stop Voltage VCC(OFF) 5-3 (Power supply voltage at which device stops operating)
Measurement circuit 1, VCC = 15.7 through 9 to 11 V 91011V
Circuit Current In Operation ICC(ON) 5-3 (Inflow current into power supply terminal, in operation)
Measurement circuit 1 ––4mA
Initialization Circuit Current ICC(OFF) 5-3
(Inflow current into power supply terminal,, while subject to
UVLO prior to operation)
Measurement circuit 1, VCC = 12 V
––25μA
Center Switching Frequency fosc(av) 8-3 (Center oscillation frequency of D terminal)
Measurement circuit 2 60 67 74 KHz
Frequency Jitter Deviation Δf 8-3 Maximum frequency – minimum frequency
Measurement circuit 2 4.0 6.7 9.4 kHz
Maximum Duty Cycle DMAX 8-3
(Maximum width of the low portion of the D terminal
waveform)
Measurement circuit 2
70 76 82 %
FM High Voltage VHFM 2-3
(VFM at which the FM current is changed from 10 μA to
–10 μA)
Measurement circuit 2
4.0 4.5 5.0 V
FM Low Voltage VLFM 2-3
(VFM at which the FM current is changed from –10 μA to
10 μA)
Measurement circuit 2
3.2 3.6 4.0 V
FM Outflow Current IsorcFM 2-3 Outflow current from FM terminal at VFM = VLFM (3.7 V typ.)
Measurement circuit 2 7.7 11 15.4 μA
FM Inflow Current IsinkFM 2-3 Inflow current into FM terminal at VFM = VHFM (4.4 V typ.)
Measurement circuit 2 –15.4 –11 –7.7 μA
OCP Threshold Voltage VOCP(th) 1-3
(The drain current at which the low portion of the D
terminal waveform becomes shorter than the high portion,
with VOCP increasing)
Measurement circuit 3
0.67 0.74 0.81 V
Leading Edge Blanking Time twb 8-3
(The low portion of the D terminal waveform with
VOCP = 1 V)
Measurement circuit 3
240 350 460 ns
Burst Threshold Voltage Vburst(th) 4-3
(FB/CC/OLP terminal voltage at which D terminal
waveform oscillation stops due to VFB decreasing from 5 V)
Measurement circuit 4
1.0 1.12 1.24 V
OLP Threshold Voltage VOLP(th) 4-3
(FB/CC/OLP terminal voltage at which D terminal
waveform oscillation stops due to VFB increasing from 5 V)
Measurement circuit 4
7.3 8.6 9.9 V
Output Current at OLP
Operation IOLP 4-3 (Outflow current from FB/CC/OLP terminal at VFB = 8 V)
Measurement circuit 4 12 18 25 μA
OLP Delay Time TOLP 4-3 (Time between surpassing VOLP(th) and stop of oscillation)
Measurement circuit 4 0.84 1.2 1.56 s
Maximum Feedback Current IFB(MAX) 4-3 (Outflow current from FB/CC/OLP terminal at VFB = 0 V)
Measurement circuit 4 220 310 430 μA
Continued on next page…
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
6
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
ELECTRICAL CHARACTERISTICS for Controller (MIC) continued, valid at TA = 25°C, VCC = 18 V, unless otherwise specified
Constant Current Set Voltage VSET(CC) 4-3
(FB/CC/OLP terminal voltage at which IFB changes from
310 μA to 16 μA due to VFB increasing from 5 V)
Measurement circuit 4
4.9 5.8 6.7 V
Constant Current Reset
Voltage VRES(CC) 4-3
(FB/CC/OLP terminal voltage at which IFB changes from
16 μA to 310 μA due to VFB decreasing from 8 V)
VRES(CC)
× VCC = 25 V, Measurement circuit 4, VCC = 25 V
3.5 3.9 4.3 V
Start-Up Current Istartup 6-3 (Outflow current from VCC terminal at VDD = 600 V)
Measurement circuit 5, VCC = 13 V 0.77 1.1 1.43 mA
OVP Threshold Voltage VCC(OVPth) 5-3
(VCC at which the oscillation of the D terminal waveform
stops due to VCC increasing from 18 V)
Measurement circuit 1, VCC = 18 through 31 to 35.2 V
28.8 32 35.2 V
Latch Circuit Sustaining
Current1ICC(H) 5-3
(Inflow current into VCC at VCC = 8.4 V, after OVP
operation)
Measurement circuit 1, VCC = 35.2 to 8.6 V
– – 270 μA
Latch Circuit Release
Voltage1VCC(LaOFF) 5-3
(VCC at which ICC drops below 20 μA due to decreasing
VCC after OVP operation)
Measurement circuit 1, VCC = 35.2 through 5.9 to 8.6 V
5.9 7.2 8.6 V
Thermal Shutdown Operating
Temperature TJ(TSD) 125 140 – °C
ELECTRICAL CHARACTERISTICS for MOSFET, valid at TA = 25°C, VCC = 18 V, unless otherwise specified
Drain-to-Source Breakdown
Voltage VDSS 8-1 Measurement circuit 6, ID = 300 μA 650 – – V
Drain Leakage Current IDSS 8-1 (Inflow current into D terminal at VDD = 650 V)
Measurement circuit 5 – – 300 μA
On-Resistance RDS(ON) 8-1 Measurement circuit 3, ID = 0.4 A – – 2.8 Ω
Switching Time tf8-1 Measurement circuit 2 – – 250 ns
Thermal Resistance Rθch-F
Between channel and internal frame; measured at the root
of terminal 3 – – 52 °C/W
1Latch circuit enabled when OVP and TSD in operation
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
7
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
0V
13V Vcc(ON) Vcc(OFF)
18V
Ic c ( OFF)
Vcc
VD
Ic c
18V
Vcc(La.OFF)
8.4V
Ic c ( H)
Vcc
VD
Ic c
Vcc(OVP)
Ic c
36V
150µA typ. 4µA
typ.
1 2 3 4
8 7 5
S/OCP FM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
A
10V
1µF47nF
Vcc
+
Ic c
VDD
VD
5.1V
GND
V
D
V
FM
VL
FM
VH
FM
VL
FM
+(VH
FM
-VL
FM
)/2
V
CC
18V
I
FM
fosc(av)
T1
I
sinkFM
fosc(Hi) fosc(Lo)
T2
·Dmax=T2/T1 100
·Δf =fosc(Hi)-fosc(Lo)
I
sorcFM
0µA
1 2 3 4
8 7 5
S/OCP FM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
10V
1µF
Vcc
100 Ω
100 Ω
+
V
DD
V
D
5.1V
GND
A
V
FM
I
FM
18V
0V
10V
90%
10%
tf
V
D
Vcc
18V
VD
VOCP
Vocp
VD(Lo)
Tbw
·RDS(ON)=VD(Lo) /0.4
0V
1V
1 2 3 4
8 7 5
S/OCPFM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
1µFVcc
+
VD
5.1V
GND
47nF
VOCP 18V
ID
0.4A
Measurement Circuit 1
Measurement Circuit 2
Measurement Circuit 3
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
8
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Vcc
Vburst
VFB
VD
V(HYS)
0V
IFB(MAX)
IFB
VOLP
IOLP
VSET(CC)
8V
18V
VRST(CC)
18µA typ. 310µA typ.
310µA typ.
TOLP
25V
1 2 3 4
8 7 5
S/OCP FM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
10V
1µF
IFB
+
VDD
GND
Vcc
A
47nF
VFB
1 2 3 4
8 7 5
S/OCP FM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
1µF
+
V
DD
GND
Vcc
A
I
D
A
Ic c
1 2 3 4
8 7 5
S/OCP FM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
1µF
+
GND
Vcc
Ic c
I
D
V
D
V
18V
300
µA
L
1 2 3 4
8 7 5
S/OCP FM/SS
FB/CC
/OLP
VCCDD
STR-A6252M
1µF
+
GND
Vcc
Ic c
18V
V
DS
V
GS
V
DD
Vcc 18V
V
GS
8V
V
DS
I
L
V
DSpeak
V
DD
T
100 Ω
Measurement Circuit 4
Measurement Circuit 5 Measurement Circuit 6
Measurement Circuit 7
()
DD
DS
DS
AS V
peak
V
peak
V
ILpeak
L
E−
=2
2
Adjust T such that ILpeak = 3.0 A
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
9
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
TYPICAL APPLICA TION CIRCUIT
For improved thermal dissipation, connect terminals 7 and 8
to as large an area of exposed copper as possible
8
7
5
1
2
3
4
VCC
D
D
FB/CC
/OLP
FM/SS
ST R-A6252
S/OCP
85~265VAC
GND
OUT
GND
PC
PC
R4
R5
Function of External Parts
Mode R4 R5
CV/CC 1 to 1.8 MΩ82 to 150 kΩ
OLP None None
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
10
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Dimensions in Inches
(for reference only)
Dimens ions in Millimeters
(controlling dimens ions )
PACKAGE DIMENSIONS, DIP-8
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
11
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
PACKING SPECIFICATIONS
510
13
0
69
14
0
524
63
145
265
520
290
135
535
T ype A T ype B
50 pieces
Stopper, with
attached tab
Orientation of Devices in
Shipping Tubes
Stopper, with
no tab
Minimum packing option: Tubes
Shipping Tube
Dimensions
Inner Carton Dimensions
Capacity: 50 tubes
per inner carton
Outer Carton Dimensions
Capacity: 4 inner
cartons per outer carton;
10,000 devices maximum
per outer carton
All dimensions: mm
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
12
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Because reliability can be affected adversely by improper storage environments and handling methods, please observe the following cautions.
Cautions for Storage
• Ensure that storage conditions comply with the standard temperature (5°C to 35°C) and the standard relative humidity (around 40 to 75%); avoid
storage locations that experience extreme changes in temperature or humidity.
• Avoid locations where dust or harmful gases are present and avoid direct sunlight.
• Reinspect for rust in leads and solderability of products that have been stored for a long time.
Cautions for Testing and Handling
When tests are carried out during inspection testing and other standard test periods, protect the products from power surges from the testing device,
shorts between adjacent products, and shorts to the heatsink.
Remarks About Using Silicone Grease with a Heatsink
• When silicone grease is used in mounting this product on a heatsink, it shall be applied evenly and thinly. If more silicone grease than required is
applied, it may produce stress.
• Volatile-type silicone greases may produce cracks after long periods of time, resulting in reduced heat radiation effect. Silicone grease with low
consistency (hard grease) may cause cracks in the mold resin when screwing the product to a heatsink.
• Our recommended silicone greases for heat radiation purposes, which will not cause any adverse effect on the product life, are indicated below:
Type Suppliers
G746 Shin-Etsu Chemical Co., Ltd.
YG6260 Toshiba Silicone Co., Ltd.
SC102 Dow Corning Toray Silicone Co., Ltd.
Soldering
• When soldering the products, please be sure to minimize the working time, within the following limits:
260±5°C 10 s
350±5°C 3 s
• Soldering iron should be at a distance of at least 1.5 mm from the body of the products
Electrostatic Discharge
• When handling the products, operator must be grounded. Grounded wrist straps worn should have at least 1 MΩ of resistance to ground to prevent
shock hazard.
• Workbenches where the products are handled should be grounded and be provided with conductive table and floor mats.
• When using measuring equipment such as a curve tracer, the equipment should be grounded.
• When soldering the products, the head of soldering irons or the solder bath must be grounded in other to prevent leak voltages generated by them
from being applied to the products.
• The products should always be stored and transported in our shipping containers or conductive containers, or be wrapped in aluminum foil.
WARNING — These devices are designed to be operated at lethal voltages and energy levels. Circuit designs
that embody these components must conform with applicable safety requirements. Pre cau tions must be
taken to prevent accidental contact with power-line potentials. Do not connect ground ed test equipment.
The use of an isolation transformer is recommended during circuit development and breadboarding.
STR-A6252M
Universal-Input 20 W 67 kHz
Flyback Switching Regulators
13
Switching
Regulators
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
The products described herein are manufactured in Ja pan by Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc.
Sanken and Allegro reserve the right to make, from time to time, such de par tures from the detail spec i fi ca tions as may be re quired to per mit im-
prove ments in the per for mance, reliability, or manufacturability of its prod ucts. Therefore, the user is cau tioned to verify that the in for ma tion in this
publication is current before placing any order.
When using the products described herein, the ap pli ca bil i ty and suit abil i ty of such products for the intended purpose shall be reviewed at the users
responsibility.
Although Sanken undertakes to enhance the quality and reliability of its prod ucts, the occurrence of failure and defect of semi con duc tor products
at a certain rate is in ev i ta ble.
Users of Sanken products are requested to take, at their own risk, preventative measures including safety design of the equipment or systems
against any possible injury, death, fires or damages to society due to device failure or malfunction.
Sanken products listed in this publication are designed and intended for use as components in general-purpose electronic equip ment or apparatus
(home ap pli anc es, office equipment, tele com mu ni ca tion equipment, measuring equipment, etc.). Their use in any application requiring radiation
hardness assurance (e.g., aero space equipment) is not supported.
When considering the use of Sanken products in ap pli ca tions where higher reliability is re quired (transportation equipment and its control systems
or equip ment, fire- or burglar-alarm systems, various safety devices, etc.), contact a company sales representative to discuss and obtain written
confirmation of your spec i fi ca tions.
The use of Sanken products without the written consent of Sanken in applications where ex treme ly high reliability is required (aerospace equip-
ment, nuclear power-control stations, life-support systems, etc.) is strictly prohibited.
The information in clud ed herein is believed to be accurate and reliable. Ap pli ca tion and operation examples described in this pub li ca tion are
given for reference only and Sanken and Allegro assume no re spon si bil i ty for any in fringe ment of in dus tri al property rights, intellectual property
rights, or any other rights of Sanken or Allegro or any third party that may result from its use.
Copyright © 2006 Allegro MicroSystems, Inc.
This datasheet is based on Sanken datasheet SSE-23421
