LNK417 INPUT VOLTAGE PROBLEM

Posted by: aliaykan on 03/27/2014

Hi,

I designed a 50V/500mA Led Driver. Output voltage and current working normal. My design according to 190-260 VAC, Non-dimming. But LNK417 goes to restart mode when input voltage reaches above 185VAC. Under 185VAC to 90VAC operating normally.

Input:

1. 190-260VAC

2. Non-Dimming

Transformer:

1. EFD30 Core

2. Primer 47T+48T (1X27AWG)

3. Bias 25T (1X27AWG)

4. Seconder 60T (2x27AWG)

Thanks for all replies,

Ali AYKAN

Files

Attachment	Size
SCHEMATIC1 _ PAGE1_4.pdf	17.59 KB

Comments

Hi Ali,

Auto restart in LinkSwitch-PH designs happens when the IFB current falls below IFBAR. On your schematic, this can probably happen if you're falsely triggering the OVP circuit that pulls down the IFB pin. Monitor this circuit and make sure its not falsely triggered.

You can also probe theactual bias voltage and back calculate your IFB and make sure it match or close to the spreadsheet value. If you can attach the spreadsheet your using, much better so I can help you better. Pls alos attach the schematic with values and if possible showsome waveforms.

Regards

Dear Dunwel,

I took notice input bulk capacitor (C4) effecting the input operating voltage and also output current. Larger capacitances (calculated is 270nf/600V) provides larger input voltage but harmonics&PF effecting negative. I'll try this and share the result..