TPS40428: No output at hot

Srinivas Jagarapu1

Part Number: TPS40428
Other Parts Discussed in Thread: CSD95378BQ5M

Hi Team,

We were testing our unit in thermal chamber, at 55C (chamber's temperature).

The unit didn't come up some times until we do power cycle.

In the state where the unit didn't come up, reduced the chamber temperature to 25C and measured the TPS40428 output. we saw 0V.

Did quick checks enable and LDOs outputs all were good, but didn't see PWM output. After power cycle we see again output +0.85V.

Please find the attached schematic of TPS40428.

Experts, please let me know what could be the reason or what to check further.

Regards,

Srinivas

TPS40428.pdf

over 4 years ago

0 Nastasha over 4 years ago

TI__Genius 10000 points

Hi Srinivas,

Can you tell me whether there was load on the output when the device was in the thermal chamber?

Thanks,

Nastasha

0 Srinivas Jagarapu1 over 4 years ago in reply to Nastasha

Prodigy 130 points

Yes load was there. TPS40428 is in our custom design board, it supplies 0.85V to FPGA.

Regards,

Srinivas

0 Nastasha over 4 years ago in reply to Srinivas Jagarapu1

TI__Genius 10000 points

Srinivas,

Are you able to measure the loading? I am wondering if at high temp and high load, the device is reaching thermal shutdown.

Thanks,

Nastasha

0 Srinivas Jagarapu1 over 4 years ago in reply to Nastasha

Prodigy 130 points

Hello Nastasha,

I could see around 21A in fusion power design, system monitor.

Now we got different issue in another card - CSD95378BQ5M was damaged during power cycle test at 55C.

Please find the attached circuit - which was modified for better ripple.

Any thoughts, what could have gone wrong?

Thanks,

Srinivas

TPS40428_Mod.pdf

0 Qingquan Tang over 4 years ago in reply to Srinivas Jagarapu1

TI__Expert 3525 points

Hi Srinivas,

As I replied your power down sequence in your another post, the power down sequence may cause the damage you mentioned here.

About the no output at hot issue, do you see output before you ramping up the chamber temp? And when you see no output, can you see any fault flagged and if you can measure the TAO signal to confirm?

Power management

Power management forum

TPS40428: No output at hot