TOP246YN temperature protection
In 2005 I designed for my company a low power Flyback using the TOP246YN (85-265Vin, 35Vout, 40W load).
Since then, more then 100kpcs have been placed on market with no problem whatsoever.
In the last 2 years there have been several supply-chain "mix-ups" (different board suppliers with different component sources, etc.) while the original design remained unchanged.
Now, I'm posting here because the last board supplies (several hundreds) seems to be affected by a structural problem of the TOP246YN.
In particular, the actual board supplier affirms that the TOP246YN he bought and assembled suffers a problem related to temperature protection.
It seems that the temperature protection threshold is much lower then expected, since even at 50°C/60°C (case temperature) the device shuts-off, and this happens on the xx% of the assembled components.
Tests have been carried out on the bare parts (just picked from the tube and tested prior to heat-sink mounting and soldering) and above mentioned behaviour seems to be confirmed.
Has anyone else encountered this problem?
Is it possible that a defective batch has been released on the market?
Thank you for your kind attention.
Comments
Thanks for Posting your Question into forum? As Our TopSwitch has inbuilt thermal shut down feature , at Min 135 deg , the part can shut down as per the datasheet. As Your case temperature is 50 deg or 60 deg, could you measure the temperature of TopSwitch by connecting ThermoCouple to the Source see whether the TOPSwitch temperature is beyond 135 deg at Full Load ? Also Contact our Local Sales Agent near to you and explain the problem.
Regards,
PI-KSAN
Thanks for your kind reply.
We are in contact with our Local Sales Agent and a visit is on schedule for next week.
In the meantime we have on the bench a sample of our power supply where the TOP246YN stops working at 68°C, and returns operative as soon as the temperature drops to around 40°C.
Temperatures have been measured with a thermocouple placed on the component tab, and also with a Dostmann Proscan 530 Dual Focus infrared thermometer. The data is consistent.
Our main concern is about batch supply quality; we are asking ourselves how such behaving components can eventually reach the market, and if this has happened somewhere else before.
Ok, Thanks a lot for getting back to us regarding the issue. As you are in contact with our local sales agent, they will help you in resolving this issue and please let them know all your conerns .
Regards,
PI-KSAN
Sorry.... errata corrige:
"xx% of assembled components" is "20% of assembled components".