TPS62932: TPS62932DRLR

Ali Khan

Expert 1095 points

Part Number: TPS62932
Other Parts Discussed in Thread: TPS62933

Tool/software:

Issue Description:

Designed a DC-DC converter for a specific application.
The converter worked fine initially but encountered an issue when the BMS wire was connected/disconnected from the board.
D5 diode was damaged due to this event.
The BMS was supplying power to the board from an 8-cell battery (25.6V nominal).

Questions:

Possible Cause of Failure:
- Could low-voltage-rated diodes have caused the issue?
- Could the issue be due to hot-plugging, since the BMS was ON when the cable was connected?
Protection for Next Revision:
- Looking for a protection mechanism for the second revision of the board.
- The goal is to prevent damage even if the BMS is ON and the power supply is connected directly while plugging in the cable.

Would appreciate any insights or recommendations on possible protection solutions.

3 months ago

0 Gui He 3 months ago

TI__Mastermind 26526 points

Hi Ali

Was U3 undamaged ? And how about Q2?

For the Hot-plugging risk, can you measure the Vin voltage when plug-in? Please probe close to the IC Vin& GND pin.

From what I see, when V_SPLY is applied 25.6V, the Q2 VDS is -20V, could that cause risk?

Thanks and best regards.

0 Ali Khan 3 months ago in reply to Gui He

Expert 1095 points

Hi Gui He
D5 was cooked then I checked Q2. It was all short. I removed D5 and Q2. The U3 is also short. So it seems like all components in VIN rail are damaged.

Thanks

0 Ali Khan 3 months ago in reply to Ali Khan

Expert 1095 points

One thing, I want to mention here that i was using this board with same BMS supply for quite few days. It only happened when I plugged in board without turning OFF BMS. BMS turn ON/OFF feature also not working any more but rest part is working so it also damaged BMS board as well.

Thanks

0 Gui He 3 months ago in reply to Ali Khan

TI__Mastermind 26526 points

Hi Ali

"i was using this board with same BMS supply for quite few days."---how did you power up the circuit? Did you Turn on the BMS power supply (V-SPLY) while the VCC_5V is on?

Does the input of BMS board to TPS62933 board has a long cable? The parasitic inductance on the input rail might reduce the Vin ringing and overshoot.

Thanks and best regards.

0 Ali Khan 3 months ago in reply to Gui He

Expert 1095 points

It wasn't the long cable. Probably 10" long cable.

Now my concerns is how i can avoid it in future design.

I have USB PWR to upload program and the BMS supply. I need a circuit that can switch between both and can compensate such overshoot and peak voltages.

Thanks

+1 Gui He 3 months ago in reply to Ali Khan

TI__Mastermind 26526 points

Hi Ali

Can you use a Q2 with higher voltage rate? when V_SPLY is applied 25.6V, the VDS is around -20V.

Thanks and best regards.

0 Ali Khan 3 months ago in reply to Gui He

Expert 1095 points

Hi Gui He
Is there any TI voltage selector switch that can handle it without any issue?
Thanks

0 Gui He 3 months ago in reply to Ali Khan

TI__Mastermind 26526 points

Hi Ali

Sorry that I'm not sure, this should be from other product line, maybe you can search on ti.com and ask the corresponding expert.

Thanks and best regards.

Power management

Power management forum

TPS62932: TPS62932DRLR

Questions: