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)

Specification:-