LNK454D - for small power leds under 1.5W

Posted by: tomifi on 11/03/2012

Dear Sirs,

I'm going to use the LNK454D to supply led with 12V forward voltage and 50mA current from universal AC voltage input (85-265V). This is a about 0.6W power .

Can I use that driver to make supply for that LED? I have found in datasheet that minimum out power is 1.5W for LNK454D.

PIExpert can calculate parameters of design do power above 1.0W.

Can you tell me what is the smallest output power?

With best regards

Comments

Hi TS,

You can use this as a design reference. This is very simple and cheap solution.

http://www.powerint.com/sites/default/files/PDFFiles/der92.pdf

Regards,

PI-Jono

Dear PI-Jono,

Thank you for your answer and your suggestion about low power supplier for LED.

Can you tell me why should I use that driver above 1.5W? Your devkit RDK-268 which is basen on LNK454D work with 1.1W output power.

I ask you about that issue because I have to build power supply for 12V LED. That PSU have to work in two modes. First is 12V and 130mA (1.56W) and second mode is 12V and 60mA (0,72W). I want to change that modes by mechanical switch.

I want to change current sense resistor by switch. Tell me if I can do that? And If RDK-268 work properly with 1.1W output power maybe my PSU will work properly with 0.72?

Please if it possible answer me asap.

With best regards.

Hi TS,

Thank you for providing us the clearer application. Yes you can modify RDK-268 to 12Voutput with a switch to varry the output current from 60mA to 130mA. Approximated minimum power to avoid pulsekeeping is 0.4W therefore you still have some margin.

Note:

1. PF and THD will change depending on the output power.

2. The efficiency is higher for 12V output as compared to 3V output.

3. Evaluate thermal performance at higher power.

Regards,

PI-Jono