The STR-S5707 and STR-S5708 are specifically designed to meet

the requirement for increased integration and reliability in off-line quasi-

resonant 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 hyster-

esis, 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 over-

molded 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

I Quasi-Resonant Operation for Low EMI and High Efficiency

I Low-Power Output Standby Mode

I Indirect Feedback from Auxiliary Winding

Reduces External Component Count

I Pulse-by-Pulse Over-Current Protection

I Latched Over-Voltage and Thermal Protection

I Third-Generation Switching Transistor with Proportional Drive

I Maximum ON Time and Off Time Set During Manufacture

I Internal Under-Voltage Lockout with Hysteresis

I Over-Molded SIP with Integral Isolated Heat Spreader

Always order by complete part number:

Part

Output Current

Output Power, P

O

Number

Continuous, I

C

Peak, 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

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, V

15 V

Continuous Output Current,

1 ms Single-Pulse Output Current,

I

Inhibit Voltage, V

15 V

Over-Current Protection Voltage Range,

Package Power Diss., P

Operating Temperature Range,

T

Storage Temperature Range,

™

STR-S5708