STPMIC1 issue

[PAkRad]

Hello.

We are using the STPMIC1APQR with the electrical scheme shown in the figure.

We are using the outputs corresponding to BUCK4, LDO4, LDO2, and LDO1.

The BUCK4 and LDO4 outputs have voltage at startup, however, the LDO1 and LDO2 outputs, although we have control through the I2C (we have checked it by turning off and on the LDO4 and the VBUSOTG output), do not provide output voltage when the corresponding bit within the control register is activated from the I2C.

Best regards.

[Vincenzo · Accepted solution]

Hi PakRad,

from schematic it seems that some regulator are not used, but even if the Buck2 is not used the BUCK2IN must be connected to the Vin, some common internal blocks are supplied using also this pin. See the note in our DS at page #3 at the bottom of the Figure1.

We strongly suggest to put for each Buck converter the relative input cap close to the BUCKxIN to better filter the switching noise activity, see BUCK4IN pin (input cap is missed).

May I know which application you are powering?

Let me know

Best Regards

Vincenzo

[PAkRad]

Thank you @Vincenzo , we will add BUK2IN pin.

Regarding the input caps, all of them are in parallel, and physically there are two close to BUCK4IN.

We are powering a Radar board.