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TPS63002: Charger harming voltage regulator when in use

Part Number: TPS63002

Hello everyone,

I'm having a problem with this "simple" design of a PCB with a LiPo charger, and two voltage regulators (one to get 5V from LiPo, the other one to get 5V from 3.3v). 

I'm trying to work with the components available/in stock at the moment...

The TPS63002 works ok when supplying 1.8V to 5.5V (tested with power supply) and with battery (tested at 3.7V) and i'm getting a stable 5V output with a 0 to 150mA load.

https://www.ti.com/lit/ds/symlink/tps63002.pdf?ts=1639986060415&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS63002

The BD33FC0FP converting the 5V to 3.3V is working fine.

https://fscdn.rohm.com/en/products/databook/datasheet/ic/power/linear_regulator/bdxxfc0wefj-e.pdf

But when I try to charge the battery for a while (20-30 sec) with the switch "on" it seems to destroy the TPS63002. I'm using a MCP73831 charging at 500mA. It seems to charge ok for this short amount of time.

Then the TPS63002 outputs -0.2V instead of 5V.

https://ww1.microchip.com/downloads/en/DeviceDoc/MCP73831-Family-Data-Sheet-DS20001984H.pdf

If I replace the TPS63002 it works again.

Here is the schematic of my design.

I realise the layout design is not great and I will improve it following the guidelines in the next design but I suppose this is not causing my problem. I might be wrong.

I am also interested in finding alternatives to this design with only voltage regulator with components that would be available now but for now I'm trying to find my mistake(s) on this one.

Let me know if you need more informations.

Thanks.

  • Hi  Emeric,

    i suspecy there are some short to GND on your Pin VIN/VOUT/L1/L2 with the damaged ones, could you help to check.

    for 5V output, you should be very carefull with your PCB design for there will be some spike caused by parasitic inductor during pwm on/off. and these spike may damage your devise if they are out of spec.

    EXP: during  boost operation(Vin is much smaller than Vout), peak voltage of node L1 should be Vout+Ldi/dt. where L means parasitic inductor, di/dt should be A/ns.

    Regards

    Tao

  • Hi Tao,

    Thanks for helping me.

    So I tested the "damaged" TPS63002 and I could find any short between GND and any different pin. I also tested it directly on a PCB with a damaged TPS63002 and the result is the same.

    Do you think the layout is the only problem here that makes the design unstable? And when I'm charging the battery it finally crashes?

    Would there be anything more than changing the layout to protect the voltage regulator?

    Thanks for the explanation.

    Regards

  • Hi  Emeric,

    you are welcome. Grinning

    i am not suer, but in your case. layout should be the main reason.and somthing else is not so important. sorry to tell that it almost has no other ways but change the layout to protect the device.

    additional, the highest spike should happen when Vout is almost build up. you will get a almost 5V output and high peak current which means you will get a high di/dt. this spike should much higher than steady state. So if you can start-up your devise when output is builded up already, i think it will be much better.

    Regards

    Tao