Failure of Tiny 274, 5W output Power supply on 105degree temperature.
HI All,
I am using Tny274 on input voltage rating 400V range, with a mosfet in series with TNY274.
Our output load is of 5W.
Power supply is working fine on room temperature, but on 105degree temperature the power supply turns off.
We have observed that tiny BP pin voltage keeps increasing with increase in temperature.
It goes to 6.4V from 6.300V and shuts down the TNY 274 at6 6.4V, then BP pin voltage is then clamped to 5.85V, and power supply turns off!!!!
Can any one help me in solving this issue?????
Comments
Hi PI Team,
Yes BP Pin is clamped to 5.85V when bias winding supply is not available.
I am attaching the power supply section.
Layout
and we are having heating chamber for testing power supplies.
Please help.....
| Attachment | Size |
|---|---|
| Schematic diagram (44.35 KB) | 44.35 KB |
| Layout.png (64.9 KB) | 64.9 KB |
Hi,
Where exactly are you measuring the temperature?
Are you measuring the device temperature or ambient temperature?
Where did you attach the thermocouple to measure the temperature? Do you if the thermocouple is intact with the device while measuring the temperature?
Could you please send me the pictures of the thermal measurement setup and thermo couple attachments?
Regards,
PI-NANO
Hi,
Could you please send your schematics, PIExpert or PIxls design and PCB layout?
Could you also please describe the temperature measurement procedure that you are following?
Typical BP pin voltage is about 6.4V when it is supplied by external bias, and it is 5.85V when it is supplied by internal current source. When the power supply shuts down there is no external bias, so BP pin voltage will reduce to 5.85V, which is expected.
Regards,
PI-NANO