TPS659037: Can it replace TPS6590377 in TMDXIDK5718

Hi Rakesh,

The TPS6590379 is pin-to-pin replacement for the TPS6590377 based on http://www.ti.com/lit/pdf/sliu011 

The damage to the PMIC sounds like an EOS event and depending on the severity it may have affected other portions of your board. Have you set RESET_IN='1' already and it didn't work or you are trying to test some additional items before setting RESET_IN?

One other note is that 1.73V seems a bit low for VRTC, have you checked it in a scope shot? Sometimes a lowered measured DC value suggests that the output is toggling which is usually due to input supply instability. If you do see VRTC toggling then I would recommending checking the voltage on the VCC1 input caps on the oscilloscope as well.

I've notified the device expert to help with future questions.

Hi,

"'""One other note is that 1.73V seems a bit low for VRTC, have you checked it in a scope shot? ""

 I have checked with scope and the value is VRTC_OUT = 1.739V. VMAINS voltage was 4.15V.

Scope shot showed a stable DC value  with no toggling with PMIC_RESET_IN = '0'.

""Have you set RESET_IN='1' already and it didn't work or you are trying to test some additional items before setting RESET_IN?"""I have tried this with current limit (500mA) but device tripped so didnt try this again.

By observation is that at 4.5V input 150mA current is drawn continuously with PMIC_RESET_IN = '0'. PMIC temperature shows temperature rise from 31C to  39C. 

Rakesh,

Have you measured the input voltages and output voltages of each SMPS rail? Also, is this observation occurring on an EVM you bought, or on your board modeled after the EVM?

If it is your board, please share the schematics.

If it is the orderable EVM, please verify if any changes have been made to the board.

Thanks,

Nastasha

This is for AM5718 EVM. Board failed without any hardware changes. Guess the cause could be some mishandling. As mentioned there was a bulge on PMIC and used to heat up when powered.

So now we have replaced PMIC with new part.

Schematics reference is of EVM.... All signal names are from Schematics....

I have measured smps rail voltages with pmic reset. All of them shows zero. This is applicable to ldo outs too. I was expecting VOutadc to show a voltage out even on reset. Except for VOUTRTC =1.739V all other rails shows zero.

Rakesh,

Thanks for the additional information. The PMIC is definitely damaged, as noted by the bulge and high heat you observed. If the second unit placed on the board is showing similar behavior, there is likely something shorted to ground on the board somewhere. SMPSx_IN pins should have the same voltage as VCC1, not 0V. Also, GPIO_5 needs to be high to turn on the device. Are you able to measure if power is shorted somewhere on the board?

Thanks,

Nastasha

It's SMPS_out voltage that is 0V.... SMPS_IN is VMAINS  4.15V.,..

Rakesh,

If this is on the new unit, it looks like you do not have an ON request present. Supply power to VCC1 will not enable the output rails of the device. You need to ensure that GPIO_5 is pulled high if you are using an enable signal. Another option is to have a press button on PWRON pin if you need a button as the input. If you are using RESET_IN, this pin should also be pulled high.

Can you measure these 3 signals?

Thanks,

Nastasha