TINY SWITCH TNY274G AUTO RESTART PROBLEM

Posted by: jkpbala on 03/07/2012

Hi,

We are using Off-line switcher “Tiny Switch - TNY274GN-TL” in our design which is used for motor speed control application. Yesterday We powered ON the proto module, we observed that the TNY274GN-TL keep on enter into Auto Restart. Please provide technical support to resolve the issue.

Details for your reference.
Input to Board: Universal – 85VAC to 265VAC
HVDC – Link voltage: ~ 330VDC
Output section: 3.3VDC @ 200mA, 5VDC @ 65mA, 15VDC@ 60mA

No overload & short circuit observed at output side.
Enable pin not pulled low (may be suspect)

I have attached schematics & waveforms captured for your reference.

Thanks,
Bala

Files

Schematics_1.pdf (112.48 KB)

Waveforms.zip (99.05 KB)

Comments

Enable pin pulled low would not cause auto-restart. Your loop is open either from faulty feedback path or overload which can include incorrect transformer or transformer connection

Hi,

When I changed the capacitor conected with BP/M pin to 100nF (from 10uF,C51 in the schematics), auto restart (2.5sec once) is not happening instaed of the it is switcing for 64msec for every 250msec once. Please see the attaced waveforms for your reference.

I have attached the transforer datasheet also for your reference.

Please let me know how to resolve this issue.

Have you gone through the waveforms which i attached in the earlier post, any findings from that?

Thanks,
Bala

Need to see drain current in profile and detail. Looks like something isn't right with your feedback hook-up. Have you checked circuit thoroughly for proper connections?

You should try to use rc circuit instead of zener diode in clamp circuit.

If you insist to use zener, you should chose soft start diode..

Best Regards

Erhan YILDIZ