DER-045: 12V @ 150mA, 85 ~ 265VAC in


This document is an engineering report describing a 12V, 150mA non-isolated power supply using a LNK304 from Power Integrations.

This document contains the power supply specification, schematic, bill of materials and measurements results.

The LNK304 is used in a non-isolated buck-boost topology. The voltage across L1 is rectified and smoothed by D1 and C2 during U1’s off-time. To a first order the forward voltage drop of D2 (slow diode used in the tests) and D1 (must be an ultrafast) can be considered similar. Therefore the voltage across Cfb tracks the output voltage. The voltage across Cfb is sensed and regulated via the resistor divider Rfb-Rbias connected to U1’s FB pin. The LNK304 switching algorithm regulates the FB pin to 1.65V +/- 7% over temperature. A small pre-load resistor has been added (Rload with 5mA current consumption) for operation down to 0mA output current.


Manufacturer Power Integrations
Category AC/DC and DC/DC Conversion
Sub-Category AC/DC SMPS - Single Output
Eval Board -
AC Voltage 115 V
230 V
Universal (115 / 230V)
Outputs and Type 1 Non-Isolated
Voltage Out 12 V
Current Out 150 mA
Output Power 1.8 W
Features Current Limit (Adj. or Fixed)
Frequency Jitter for EMI
Open Circuit Protection
Short Circuit Protection
Thermal Protection
Efficiency @ Conditions >65%, 120 ~ 265 VAC, 12V @ 150 mA
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 2005-04
Date Added To Library 2014-07

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