TNY280 breakdown

TNY280 breakdown
We use the component to 2 years. However 10% of our
product returns with burned TNY280. Literally explodes.
You could look at our schematic and point out the fault?

I'm Brazilan!

Dear friend, optocupler must be connected to pin 1 of TNY280 and not to pin 2.

My God! amateur error! I will test the change. Conclusion post here, but should be just that! The strange thing is that the power supply works with this error. I sold over 500 machines with this error! THANK YOU!

Im using tny280 as a 230 - 13,5 Dc power supply in one of my products for hotel room automationts in Greece.

There are most cases that during start up, 10ohm resistor brakes and tny280 brakes.

Any sugestionts?

Please take a look in my shematic and board (uploaded).

I have an urgent situation here.

Best regards

Kostas

Thanks for Posting your Question into forum. Is your 10 Ohm NTC Blowing? If that's the Case , How Much Inrush current is going through it. What's the Inrush Current? You can measure the Inrush Current How much is going through it by testing at Low Voltage? Could also please verify the thermal Constant of Thermistor and also verify the i2t Rating of  Bridge diode. Could you please send us the data sheet of your 10 Ohm NTC? Also test with 20 ohm NTC to verify the 20 Ohm NTC Blows up or not?

Regards,

PI-KSAN

TNY280 breakdown
We use the component to 2 years. However 20% of our
product returns with burned TNY280. and tny280 explode and burn some of them after several days breakdown please check my schematic

TNY280 breakdown
We use the component to 2 years. However 20% of our
product returns with burned TNY280. and tny280 explode and burn some of them after several days breakdown please check my schematic

High mains can easily kill the device - depending on the max flyback voltage from your transformer - on one schematic you show a 1M res across the pri side snubber cap - this is perhaps too large a value - try 100k, 1W. Adding a TVS to limit the max overshoot is helpful too if the mains goes above 265Vac.

If you have a scope look at the worst case turn off voltage on the device - this will tell you a lot - also if you have a spec for the max leakage inductance of your transformers ...?

hi thanks for your answer you mean to change 1mohm res too 100k where can i add tvs ???

i change 1M to 100k it become better but after 2 days tny280 burn again i didnt use C5 between pri and sec of transformer is it important or not

according to your schematic, part of your transformer is shorted - need to fix this - what is the total leakage L referred to the pri?

this short is connected to shild its work but after several times i swith off and on my ac input my 2ny280 burn or after several days its work its burn and we product about 1000 pcs and i dont know what can i do

Hello people. We solved our problems of the TNY280 and TNY268 by adding to the project a TVS to limit the peaks of tension that eventually arose between drain and source. We also add a 10R / 5W NTC at the AC input before the bridge. Another care is the distance between tracks on all tracks that have high voltage conducting. Summing up. Follow exactly what the datasheet recommends.
Another important thing is to get the components from power. These actions reduced the problems we had to zero.

Hello, we use TNY268 in our scheme and we have a problem with 20% of our products. product returns with burned TNY268.

if you buy TNY268 from unknown quality 3rd party vendors - you may have this problem ... does the fuse blow?

We only buy the scheme here https://store.comet.bg/en/Search/?keywords=tny268#eyJpcHAiOiIyMCIsIm0iOiIiLCJrIjoidG55MjY4In0%3D

Yes, the fuse is burn, but not to protect it TNY268.
In the event of a defect, the repair is required to replace TNY268, optocoupler and both zener 5,1V/ 8.2V.

This is a picture of the PCB board topology

given that the chip is supposed to shut down if too hot, that leaves suspect chips or too high a leakage spike on the Tx or zeners are failing due to low quality - can you post scope shots of drain?

Here are the pictures of drain.

that scope shot looks normal for a simple wound primary with a fair bit of winding capacitance - obviously running at light load ....

Hi invest,
Your schematic does not match the component designation in your PCB layout. Can you please send a schematic that match the PCB? Also, can you help us give more details of the failure? At what input voltage does the device failed? What is running at full load condition? Is it during start-up or normally running then blew-up? What's your output power and please help send your transformer specs.
Regards,
Jedidiah

I have sketched the schematic..
The tny268 burnt out when powered up.. Whats the problem i cant understand. If i connect a resistor to block the inrush current what shall i connect? The transformer has 140primary turns.. Ic1 is TNY268P

IC1 Is TNY268P

Hi AD10,

Thank you for your inquiry. However, if may I suggest since this thread has been a long one, please kindly raise this question by creating new ticket or post.

Best Regards,

PI-Lupin the Third