The STR-S6707, STR-S6708, and STR-S6709 are specifically designed to meet the requirement for increased integration and reliability in off-line quasi-resonant flyback converters. These devices incorporate 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 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, these devices and their fixed frequency counterparts represent a significant advance in off-line SMPS reliability growth and integration.

FEATURES

■ Quasi-Resonant Operation for Low EMI and High Efficiency

■ Output Power to 220 W

■ Low-Power Output Standby Mode

■ 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