Off Line Switcher 7-Pin SMD-B

LinkSwitch-HF integrates a 700 V power MOSFET, oscillator, simple ON/OFF control scheme, a high voltage switched current source, frequency jittering, cycle-by-cycle current limit, and thermal shutdown circuitry onto a monolithic IC. The start-up and operating power are derived directly from the DRAIN pin, eliminating the need for a bias winding and associated circuitry. The 200 kHz maximum switching frequency allows very low flux transformer designs, practically eliminating audible noise with the simple ON/OFF control scheme using standard varnished transformer construction. Efficient operation at this high switching frequency is achieved due to the optimized switching characteristics and small capacitances of the integrated power MOSFET. The fully integrated auto-restart circuit safely limits output power during fault conditions such as output short circuit or open loop, reducing component count and secondary feedback circuitry cost. The internal oscillator frequency is jittered to significantly reduce both the quasi-peak and average EMI, minimizing filtering cost. LinkSwitch-HF combines a high voltage power MOSFET switch with a power supply controller in one device. Unlike conventional PWM (pulse width modulator) controllers, LinkSwitch-HF uses a simple ON/OFF control to regulate the output voltage. The LinkSwitch-HF controller consists of an oscillator, feedback (sense and logic) circuit, 5.8 V regulator, BYPASS pin under-voltage circuit, over-temperature protection, frequency jittering, current limit circuit, leading edge blanking and a 700 V power MOSFET. The LinkSwitch-HF incorporates additional circuitry for auto-restart.

• Output Power - Adapter : 3.5 W
• Output Power - Open Frame : 5 W
• Fully integrated auto-restart for short-circuit and open loop protection
• Self-biased supply – saves transformer auxiliary winding and associated bias supply components
• Tight tolerances and negligible temperature variation on key parameters eases design and lowers cost
• High maximum switching frequency allows very low flux density transformer designs, practically eliminating audible noise
• Frequency jittering greatly reduces EMI
• Packages with large creepage to high voltage pin
• Lowest component count switcher solution