TIDA-020047: PMIC LP876242B0RQKRQ1 have no output.

Hello,

Buck 4 needs to be enabled for 2-chip operation.  This is the RF supply for FE2.  To do this, You would need to use the SPI bus to write bit BUCK4_EN to “1” to enable BUCK4 output. SPI write 0x0A 0x00 0x33

Also, the NVM of the PMIC enables the watchdog.  While testing your board, you may wish to disable this by turning the register off.  SPI write 0x09 0x80 0xBF

Regards,

Brian

Hi Brian,

   The paradox is that the SPI is controlled by the SOC, while the SOC is powered by the PMIC, and the SOC cannot work without the output of the PMIC.

Hi, 

There is a 500 ms period at boot where the watchdog is not active.  It is during this time, that the SPI write must be done to disable the watchdog, or just begin servicing the watchdog if you intend to use it in the system.

Regards,

Brian

Hi Brian,

    We have tried to disable the watchdog by pull down GPIO2, but it is doesn't work. the SOC can't power up, we can't use SPI. Whether there are other ways to disable watchdog