Description

LinkSwitch-HFintegrates 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.

Product Highlights

Features Optimized for Lowest System Cost
• 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

Much Better Performance over Linear/RCC

• Lower system cost than RCC, discrete PWM and other integrated solutions
• Universal input range allows worldwide operation
• Simple ON/OFF control – no loop compensation needed
• No bias winding – simpler, lower cost transformer
• High frequency switching – smaller and lower cost transformer
• Very low component count – higher reliability and single side printed circuit board
• High bandwidth provides fast turn on with no overshoot and excellent transient load response
• Current limit operation rejects line frequency ripple
• Built-in current limit and hysteretic thermal shutdown protection

Applications

• Chargers for cell/cordless phones, PDAs, digital cameras, MP3/portable audio devices, shavers etc.
• Standby and auxiliary supplies