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