TOP244YN
Hello,
I have some power supplies that have the TOP244YN controlling the auxiliary power supply.
This auxiliary power supply supplies power to the PFC circuit (L4981AD), the fan and other main power circuits, which can deliver 15 A under 48 V.
I've always found the TOP244YN in half and sometimes the protection (TRF51) is not triggered.
At other times, the TRF51 protection is partially tripped, internally this TRF51 position component has a wire resistor and a thermal fuse. The TRF51 component is a WF7N internal thermal fuse resistor developed by KOA Speer Electronics Inc.
I would like to understand what is happening so that the TOP244YN is going into short circuit, to the point of blowing its casing.
The only components that are being affected are TOP244YN (Q201) the transformer (T201) and the protector (TRF51).
The transformer receives direct current permanently until its winding melts the varnish and short circuit, but does not break the coil wire
When the transformer (T201) and the protector (TRF51) have not been affected, simply replace the TOP244YN and the power supply will operate normally, but after a few months of use the TOP244YN again explodes.
Is this a heating problem?
Is the TOP244YN's internal temperature protection system not working properly?
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Note2: The TRF51 only breaks the wire resistor, the fuse remains normal
Hi RTEK1000,
Temperature protection of TopSwitch works. The common way to damage TopSwitch is when its Drain to Source Voltage exceeds 700V rating. Usually, we need to design Vds with 90% derating at all operating condition (normal operation, start-up condition, PFC start-up condition). If the absolute maximum rating of 700V is reached, TopSwitch will be damaged.
Regards,
Jedidiah
Hello,
I came to think of a peak voltage,
Any tips to prevent?
Use a TVS diode in parallel with the PFC output (cap C55)? Maybe a TVS 1.5KE480A?
Or lower the PFC voltage a bit? Maybe for 350V?
Or a 1.5KE600A for Drain to Source?
Hello,
I checked the datasheet of the PFC L4981AD (ST) controller and found pin 3, this pin has OVP (Over voltage protection) function, and according to the board resistors, the OVP must operate with 438V.
Honestly, I now believe it can be difficult to be an overvoltage problem produced in the PFC.
Hi RTEK1000,
I suggest we do actual voltage measurement across Drain to Source during normal and start-up operations so that we can factor in the Vds pikes caused by leakage inductance and also if we need to adjust the snubber and transformer turns ratio in case you get high data.
Regards,
Jedidiah
Note: The PFC will only be activated after the TOP244YN goes into operation.