TNY problem

Hi,
Thanks for sharing the information.
There are could be a whole lot of reason behind with this issue, that includes bad soldering on one part, good on the other; design is marginal that could cause variable performance with part to part variation...etc.
Here are my suggestions:
1. Put the original ICs back, make sure it is soldered in a correct way, check if the issue is still there or not.
2. If issue is still there, check the drain current, drain voltage, secondary output voltage, BP pin voltage...etc. Check if you could find some unusual waveforms or not.
3. If you could also share your design files, that I can have a check for you.

Hope this is helpful..

Hi ,
Thanks for your reply .
We Find out TNY 264's problem . as you see in the attached pictures , there are burning points under the TNY 264.
so I'd like to know answer of below questions .
1.The reason of creating these points , why these points are created ?
2.Why does TNY continue working in spite of existence of these points ?

Hi,
It is good news that you found the reason of the problem.
To ask your questions:
1. The burning points could be the over current through the internal wire bonding that heated the case of the device. It could be also some heat that generated outside (for example: pad underneath), that generated the heat, burning the case of the device.
2. The reason I can think could be the heat is not enough to brake the connection instead of only generating heat that caused the burning point. It may be still functional, but it may get some parameters derated. I won't recommend you to continue to use it even it is still functional.

Hope this is helpful

I am using TNY284PG, I designed my board based on the software recommended schematic, the output voltage is 12v, for no-load condition the input power supposed to be less than 150mw, but in my case it is about 1w at 265v. could you please help me what is wrong with this circuit

Hi:

May I request how you did the measurement for the input power? What is the equipment you used for the input power measurement? Thanks

Hi,

We are using tny280 on a product and some of them faile on  the first test.

 we increase the AC voltage gradually and good items work from 50V and bad ones don't switch at all.

and when we replace them everything is ok.

I have been using TNYs for 12yrs  and I am familiar with  the design. We also check the soldering temperature and its around 240c.

And the power consumption of the product is just 4 watts and I used 280 because we had it in stock.

Our major concern is the reliability of products we sell because there are some after sale failures .

I think these products from china have poor quality control.

Any comment appretiated

Hello mehrshad,

Thank you very much for using power integrations product and sorry for the late reply.

As you mention the parts are from China. Can you provide us the source you get those part, the distribute and website if possible. we want to track those information.

When you mention the bad parts didn't switch, can you see any voltage at the BP pin?

Thanks again for your interest of TNYs.

Best Regards

Hi,

I have same problems in using TNY278,TNY280 like mehrshad.I'm agree with him!

some of mentioned parts in the first few minutes of use explode and source and drain pins shorted togehter.

and the problem is solved when we replace a similar TNY again.

i think low quality control, cuases this issues.

Do you have any other reports or feedback?

Hello Shahriar,

Thank you for interested in Power integrations produtcs.

Before we draw any conclusion about the quality control, may I ask where did you get these ICs, distributors or website if possible. If you can share more information about these IC, like any document about the pruchase, that will be even better.

When you mentioned the drian pin is shorted to source pin, how do you measure it and what did the circuit responed when the parts failed, is it blowed up? Do you have any picture about the failure parts.

Best Regards

Hello Sir,

Thanks for the follow-up.

For a period of three years or less, I faced with this problem. During this period, about 40% of the (TNY280 or TNY278) Replacement fails, which led to the replacement again of this parts.(only in this Series of TNYs )

I’ve done several tests. In the first places, I suspect counterfeit ICs used. Then I prepared those parts from other authoritative source in my country (IRAN) like www.Payaelectronic.ir : this company is the biggest and the most reliable company in the supply of electronic components in Iran.

I put the power supplys section which include those ICs, under load 250mA in 12v (output) and to prevent the explosion IC in the workshop I put an AC 220v 60W filamentary bulb lamp in series.

After about 5 min. the mentioned lamp is lite in the sense that there is a short circuit and output power goes off. This could be checked by measurement resistance between source and drain pins in TNY by a simple multimeter of course after cutting of input power. For this reason mentioned IC in attachment photo unexploded but it has short circuit inside, unfortunately there are many blowup cases.

Best Regards.

Hello Shahriar,

Thank you for the detailed reply. I will confirmed with our product team to confirm if these parts are counterfeit or not.

At the same time, can you share the schematic of you power supply? Did you ever measure the drain to source voltage acorss the D&S pin of tiny swicth at the maximum possible input voltage like 265V and full load condition? if you can share these information with us, we can dig in deeper to see if these is any design issue causing this problem.

Best Regards