TPS63802: Device burns for unknown reason

Hi   Danilo,

i think the inductor should not be the root cause.

do you find any pins shorted to GND?  espicially Pin Vin L1 L2 Vout, could you help to check?

Regards

Tao

Hi Tao,

According to our customer,

Unfortunately the chips are so small I can't find them.

I understand this is a problem, but can you tell me if the design of the PCB and the electrical circuit is correct?

If another power supply burns, I'll save the chip.

Regards,

Danilo

Hi   Danilo,

the schematic is ok and layout is not bad.

input part has a good layout but it is voltage is high and output put has a not so good layout but the voltage is lower.

i am not sure. but find which PINs shorted to GND is important to get the root cause. 

once we get the PIN shorted, we can do some bench to confirm with same board but different devices.

Regards

Tao

Hi Tao,

Here is the response of our customer.

I found that I have a sort circuit of 3.3V in the periperal of the board,  This caused a current of 1.5A for a long time and this is probably what caused the chip to burn.

1. Is it possible to set a current limitation in the supply to prevent such a case?

2. Input part has a good layout but it is voltage is high and output put has a not so good layout but the voltage is lower.

a. What do you mean you say “voltage is high”?

b. And what can I improve on the output?

Regards,

Danilo

Hi   Danilo,

1. Is it possible to set a current limitation in the supply to prevent such a case?

device itself? no, it is impossible. it should be done with a complex external circuit. and i think it is unnecessary.

2. Input part has a good layout but it is voltage is high and output put has a not so good layout but the voltage is lower.

a. What do you mean you say “voltage is high”?

the input voltage is 5 volt, right? i mean 5V is a high voltage for this device. 

b. And what can I improve on the output?

without re-design of layout, you can swap the location of C5 and C12, also during bench, i think you can connect the Gnd of output cap to Pin GND of device with a thick and short wire. it will help to find the root cause, i think the damaged device is caused by the parastic inductor.

once we find the root cause. we can redesign the layout and make sure the parastic inductor of main power loop is as small as you can.

the layout example in DS is really a good one.

Regards

Tao

Hi   Danilo,

Same hope from my side

Regards

Tao