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LNK302 shuts down for ~10 sec

Posted by: ykolerov on

Hi,

I'm using lnk302 in a buck topology to produce 12V in an EMI-noisy device. At some point, lnk302 shuts down for ~9.5 seconds, and then goes on. The temperature does not hit 60C. Any ideas what could it be?

thanks,

Files
schematic (23.8 KB)
waveform (122.2 KB)

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Submitted by PI-Jedidiah on 04/29/2019

Hi ykolerov,
You are using Capacitors with polarity in your schematic. It would be best if you could correct your schematic with proper polarity unless you really placed the capacitors in such orientation which will cause your circuit to not operate.
What's the value of your R6? Can you send with values also for all your parts in the schematic? What's the output current you design? 12V and what output current?
Regards,
Jedidiah

Submitted by ykolerov on 04/30/2019

Sorry - I just used this symbol for capacitors "-)|-" because I couldnt find this one "-||-" in my CAD. Yes, sound silly, really sorry for misleading you. :-( All caps with polarity have "+" marks, all others are non-polar ceramic.

R6 = 3k3

VAC = 230V
V at D3 anode = 12V
V at U2 output = 5V
PWM frequency is ~33 kHz, duty changes from 0 to 100%
P between outputs is ~120 W - there are 3x40W incandescent lamps, so the output current rms is ~0.5A at 100% duty, peaks could go up to 0,74A at tops of AC sine wave

All other values are in the newly attached file.

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schematic with values (23.13 KB) 23.13 KB
Submitted by PI-Jedidiah on 05/08/2019

Hi ykolerov,
What's the expected power you design for LNK302 circuit to deliver?
Regards,
Jedidiah

Submitted by ykolerov on 06/09/2019

11mA RMS

Submitted by PI-Jedidiah on 06/11/2019

Hi ykolerov,
Hi I don't find any auto-restart 10s timer inside LNK302. Maybe, we should check other waveforms that can cause the 10s auto-restart such as VDS or BP Pin.
Regards,
Jedidiah