LNK305PN IC – Power Integrations – AC-DC Off Line Switcher IC

The LNK305PN 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 Figure 1. Typical Buck Converter Application (See Application Examples Section ? ?for Other Circuit Configurations).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 fly back converters. The fully integrated auto-restart circuit in the LNK305 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.

Features:-

? Lowest cost and component count buck converter solution

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

? 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)