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TPSM846C23: TPSM846C23- Can't get output

SRI RAJA SUMAN R
Prodigy 90 points
Part Number: TPSM846C23

Tool/software:

Hi,

1) Without PMBus

In my Board , I've designed  TPSM846C23 power module to get 0.8V output.  In Datasheet mentioned that, it is possible to operate the module without the need for a PMBus interface. To set the output voltage, the adjustment method requires a resistor, RSET, connected between the FB pin and AGND . But while im testing board i couldn't get desired output. i removed all pullup resistors and given 3.3V pullup for CNTL pin. But still get output

Here i'll attach my design schematics.

2)With PMBus

I've used Aardvark i2c mode, i can communicate with TPSM846C23 ,i tried updating the OPERATION register to 80h and ON_OFF_CONFIG to 00h (able to access the registers using Aardvark tool), but that also not giving any output. Please help me to resolve this asap.

Regards,

SUMAN

 

  • 0
    TI__Expert 3218 points

    Hi Suman,

    Without PMBus: What voltage are you getting without PMBus? You mentioned you got some output but not the correct one.

    With PMbus: What are you reading for VOUT_COMMAND and VOUT_SCALE_LOOP commands?

    One thing to look is CNTL setup, by default (factory) device is set to "active high" for CNTL pin, if you change ON_OFF_CONFIG (02h) = 00h, then you are changing it to "active low" meaning CNTL would have to be connected to GND to enable the device.

    Based on your schematic below it looks like you need "active high" mode to enable the output, since you have 3.3V connected to pullup resistor.

    This can be changed through 02h[bit1]:

    Make sure when doing this change to save to NVM else the change will disappear when your power on the device again. This can be done through STORE_DEFAULT_ALL (11h) command.

    Regards,

    Eileen