Allegro STRS5708, STRS5707 Datasheet

The STR-S5707 and STR-S5708 are specifically designed to meet
the requirement for increased integration and reliability in off-line quasi­resonant flyback converters with indirect feedback. Each device
incorporates the primary control and proportional drive circuit with a
third-generation high-voltage bipolar switching transistor.

Crucial system parameters such as maximum ON time and OFF
time are fixed during manufacture. Local control circuit decoupling and
layout are optimized within each device.

Cycle-by-cycle current limiting, under-voltage lock-out with hyster­esis, over-voltage protection, and thermal shutdown protect these
devices during all normal and overload conditions. Over-voltage
protection and thermal shutdown are latched after a short delay. A
primary-side error amplifier with reference is included to facilitate
regulation from an auxiliary or bias winding of the power transformer. A
versatile triple-level inhibit circuit includes the OFF time synchronization
required to establish quasi-resonant operation. The inhibit function has
also been expanded to initiate operation in stand-by mode in which the
power supply delivers a small fraction of the steady-state output power.
The dual requirements of dielectric isolation and low transient thermal
impedance and steady-state thermal resistance are satisfied in an over­molded single-in-line power package.

Proven in substantial volumes, this device and its fixed-frequency
counterparts represents a significant advance in off-line SMPS reliability
growth and integration.

FEATURES

■ Quasi-Resonant Operation for Low EMI and High Efficiency

■ Low-Power Output Standby Mode

■ Indirect Feedback from Auxiliary Winding

Reduces External Component Count

■ Pulse-by-Pulse Over-Current Protection

■ Latched Over-Voltage and Thermal Protection

■ Third-Generation Switching Transistor with Proportional Drive

■ Maximum ON Time and Off Time Set During Manufacture

■ Internal Under-Voltage Lockout with Hysteresis

■ Over-Molded SIP with Integral Isolated Heat Spreader

Always order by complete part number:

Part Output Current Output Power, P

O

Number Continuous, ICPeak, I

CM

Wide AC In 220/240 VAC In

STR-S5707 6 A 12 A 90 W 140 W
STR-S5708 7.5 A 15 A 120 W 180 W

Data Sheet

28114A*

OFF-LINE SWITCHING REGULATORS

– WITH BIPOLAR SWITCHING TRANSISTOR

+

OVER-CURRENT

PROTECTION

BASE

COLLECTOR

UVLO

COMMON

V

IN

Dwg. PK-004

INHIBIT

FAULT
LATCH

REF.

1

2

3

4

5

6

7

OSC.

R

S

FAULT

8

9

SINK

DRIVE

+

DRIVE

32 V SENSE

+

ABSOLUTE MAXIMUM RATINGS

Supply Voltage, VIN........................... 15 V

Output Voltage, V

CEX

....................... 850 V

V

EBO

................................................ 7 V

Continuous Output Current,

IC.......................................... See Table

1 ms Single-Pulse Output Current,

ICM........................................ See Table

Sink Current, IS................................. 1.5 A

Drive Current, ID.......................... -700 mA

Inhibit Voltage, V

INH

........................... 15 V

Over-Current Protection Voltage Range,

V

OCP

............................................ ±3.5 V

Insulation Voltage,V

WM(RMS)

........... 2000 V

Package Power Diss., PD........ See Graph

Output Junction Temperature, TJ.. +150°C

Internal Frame Temperature, TF... +125°C

Operating Temperature Range,

TA............................... -20°C to +125°C

Storage Temperature Range,

T

stg

............................. -40°C to +125°C

™

STR-S5707

AND

STR-S5708

STR-S5707

AND

STR-S5708

OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]

™

FUNCTIONAL BLOCK DIAGRAM

ALLOWABLE PACKAGE POWER DISSIPATION MAXIMUM SAFE OPERATING AREA

60

40

20

20 60 100

3.2 W

140

LIMITED BY FRAME
TEMP. = +125°C MAX.

RECOMMENDED MAX.
FRAME TEMP. = +100°C

FREE AIR

54 W

0

TEMPERATURE in °C

ALLOWABLE PACKAGE POWER DISSIPATION in WATTS

MOUNTING SURFACE
TEMPERATURE

Dwg. GK-003-2

PROPORTIONAL

DRIVE

TSD

OVER-VOLT.

PROTECT

OSC.

R

S

Q

V

IN

SENSE

7

OVER-CURRENT
PROTECTION

COMMON

COLLECTOR

BASE

SINK

DRIVE

3300 pF

1 kΩ

R

ton

R

toff

0.75 V

-1 V

1.4 V

5.1 V

REF.

FAULT
LATCH

+

+

+

+

INHIBIT

9

6

8

4

3

1

2

5

Dwg. FK-001-1

UVLO

1500 pF

30

3.0

0.3

COLLECTOR-EMITTER VOLTAGE in VOLTS

COLLECTOR CURRENT in AMPERES

Dwg. GK-002-1A

1.0

10

0 200 400 600 1000

0.5

5.0

800

STR-S5708 (15 A)

STR-S5707 (12 A)

L = 6 mH
I

B1

= 2.5 A

I

B2

= 0.8 A

t

on

= 100 µs

dc < 1%

Copyright © 1994 Allegro MicroSystems, Inc.

www.allegromicro.com

STR-S5707

AND

STR-S5708

OFF-LINE

QUASI-RESONANT FLYBACK

SWITCHING REGULATORS

ELECTRICAL CHARACTERISTICS at TA = +25°C, VIN = 8.5 V, voltage measurements are refer­enced to Common (pin 2) (unless otherwise noted).

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

On-State Voltage V

INT

Turn-on, increasing V

IN

7.6 8.0 8.4 V

Under-Voltage Lockout V

INQ

Turn-off, decreasing V

IN

4.6 4.9 5.2 V

Over-Voltage Threshold V

OVP(th)

9.2 – 10.7 V

Output Leakage Current I

CEX

VCE = 850 V, VBE = -1.5 V ––100 µA

Output Saturation Voltage V

CE(sat)

STR-S5707, IC = 2 A, IB = 400 mA ––400 mV

STR-S5708, IC = 3 A, IB = 600 mA ––400 mV

V

BE(sat)

STR-S5707, IC = 2 A, IB = 400 mA ––1.5 V

STR-S5708, IC = 3 A, IB = 600 mA ––1.5 V

DC Current Gain h

FE

VCE = 4 V, IC = 1 A 29 – 61 –

Maximum ON Time t

on

33 – 41 µs

Minimum OFF Time t

off

45 – 55 µs

Over-Current Threshold V

OCP(th)

-0.88 -1.0 -1.12 V

Sense Voltage V

SENSE

I

SENSE

= 3.2 mA 31.7 32.0 32.3 V

Inhibit Threshold Voltage V

INH(th)

Oscillation stops 0.65 0.75 0.85 V

Oscillation synchronized – 1.4 2.0 V

Oscillation stops (fault latch set) 3.2 5.1 5.8 V

Latch Holding Current I

INH

VIN reduced from 10.7 V to 4 V ––500 µA

Latch Reset Voltage V

Q

IIN ≤ 100 µA, VIN reduced from 10.7 V 2.5 3.1 – V

Ref. Voltage Temp. Coeff. α

VZ

-20°C ≤ TF ≤ +100°C, IIN = 3.2 mA – 2.5 – mV/°C

Supply Current I

IN(ON)

Operating 15 – 28 mA

I

IN(OFF)

––200 µA

Insulation RMS Voltage V

WM(RMS)

All terminals simultaneous reference 2000 –– V
metal plate against backside

Thermal Shutdown T

J

125 150 – °C

Thermal Resistance R

θJM

Output junction to mounting surface – 2.0 – °C/W

NOTES: Negative current is defined as coming out of (sourcing) the specified device terminal.

Typical Data is for design information only.