CSD95378BQ5M: Is safe to have the MOSFETs enabled before the TPS40428 is programmed?

Giuseppe Forte

Part Number: CSD95378BQ5M
Other Parts Discussed in Thread: TPS40428,

I have a design that uses two CSD95378BQ5M connected through 220 nH inductors to generate a common VCCINT power supply. They are controlled by the TPS40428, but the VDD and ENABLE pins in both CSD95378BQ5M are connected together so they are enable when the board is switched on.

My question is if it is safe to have the MOSFETs enabled before the TPS40428 is programmed? I have many capacitors connected close to the 12V VIN of the CSD95378BQ5M and it has been working without problem in 10 boards, but now one of those capacitors (one of two of the 330uF rated to 16V) that is in the first CSD95378BQ5M exploded in two new boards. This can be due to many reasons, but I'm trying to pin down the problem and reduce issues in the future.

over 6 years ago

0 Brett Barr1 over 6 years ago

TI__Mastermind 18200 points

Giuseppe,
I have forwarded your question to our applications team. Hopefully I'll have an answer for you shortly.

0 Brett Barr1 over 6 years ago in reply to Brett Barr1

TI__Mastermind 18200 points

Response from apps:

"The bottom line is when the control IC is being programmed, we can’t have the power stage switch with power, which means either the power stage can’t be enabled or the 12V main supply can’t be applied."

0 Giuseppe Forte over 6 years ago in reply to Brett Barr1

Prodigy 60 points

Thanks Brett, I'll implement the changes.

0 Giuseppe Forte over 6 years ago in reply to Brett Barr1

Prodigy 60 points

Just to confirm: It means that is safe to have 12V supplied to VIN of the power stage switch (U20 on the schematic) while the ENABLE and VDD pins are connected to GND?

0 Brett Barr1 over 6 years ago in reply to Giuseppe Forte

TI__Mastermind 18200 points

Correct, this is ok.

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CSD95378BQ5M: Is safe to have the MOSFETs enabled before the TPS40428 is programmed?