DER-231: 12V @ 110mA, 85 ~ 265VAC in


This document is an engineering report describing a 12 V, 110 mA non-isolated buck converter utilizing a LinkSwitch-TN LNK304DG. The design is intended to be used for small appliance and metering applications.

The document contains the power supply specification, schematic, bill of materials, and performance data.

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.


Manufacturer Power Integrations
Category AC/DC and DC/DC Conversion
Sub-Category AC/DC SMPS - Single Output
Eval Board Board not Stocked
AC Voltage 115 V
230 V
Universal (115 / 230V)
Outputs and Type 1 Non-Isolated
Voltage Out 12 V
Current Out 110 mA
Output Power 1.32 W
Features Current Limit (Adj. or Fixed)
Frequency Jitter for EMI
Open Circuit Protection
Over Current Protection
Short Circuit Protection
Thermal Protection
Efficiency @ Conditions >70%, 90 ~ 265 VAC, 100% load
>70%, 90 ~ 250 VAC, 75% load
>70%, 90 ~ 222 VAC, 50% load
>65%, 90 ~ 175 VAC, 25% load
No-load Input Power @ Voltage - Not Given
Switching Frequency 66 kHz
Internal Switch Yes
Component Count + Extras 15 + 0
Voltage In 85 ~ 265 VAC
Design Author Power Integrations
Application / Target Market White Goods
Main I.C. Base Part LNK304
Date Created By Author 2009-09
Date Added To Library 2014-07