描述 Description

LinkSwitch-TN is specifically designed to replace all linear and capacitor-fed (cap dropper) non-isolated power supplies in the under 360 mA output current range at equal system cost while offering much higher performance and energy efficiency.

LinkSwitch-TN devices integrate 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 voltage on the DRAIN pin, eliminating the need for a bias supply and associated circuitry in buck or flyback converters. The fully integrated auto-restart circuit in the LNK304-306 safely limits output power during fault conditions such as short-circuit or open loop, reducing component count and system-level load protection cost. A local supply provided by the IC allows use of a non-safety graded optocoupler acting as a level shifter to further enhance line and load regulation performance in buck and buck-boost converters, if required.

Product Highlights

Cost Effective Linear/Cap Dropper Replacement

? Lowest cost and component count buck converter solution

? Fully integrated auto-restart for short-circuit and open loop fault protection – saves external component costs

? LNK302 uses a simplified controller without auto-restart for very low system cost

? 66 kHz operation with accurate current limit – allows low cost off-the-shelf 1 mH inductor for up to 120 mA output current

? Tight tolerances and negligible temperature variation

? High breakdown voltage of 700 V provides excellent input surge withstand

? Frequency jittering dramatically reduces EMI (~10 dB)

– minimizes EMI filter cost

? High thermal shutdown temperature (+135 °C minimum)

Much Higher Performance over Discrete Buck and Passive Solutions

? Supports buck, buck-boost and flyback topologies

? System level thermal overload, output short-circuit and open control loop protection

? Excellent line and load regulation even with typical configuration

? High bandwidth provides fast turn-on with no overshoot

? Current limit operation rejects line ripple

? Universal input voltage range (85 VAC to 265 VAC)

? Built-in current limit and hysteretic thermal protection

? Higher efficiency than passive solutions

? Higher power factor than capacitor-fed solutions

? Entirely manufacturable in SMD

EcoSmart?– Extremely Energy Efficient

? Consumes typically only 50/80 mW in self-powered buck topology at 115/230 VAC input with no load (opto feedback)

? Consumes typically only 7/12 mW in flyback topology with external bias at 115/230 VAC input with no load

? Meets California Energy Commission (CEC), Energy Star, and EU requirements

Applications

? Appliances and timers

? LED drivers and industrial controls