Product Description
LNK302/304-306 LinkSwitch-TN FamilyLowest Component Count, Energy-Efficient Off-Line Switcher ICProduct HighlightsCost 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 – save 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 SMDEcoSmart™– 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 requirementsDescriptionLinkSwitch-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 nonsafety graded optocoupler acting as a level shifter to further enhance line and load regulation.
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