PCA9420 (How to change SW2 default 1.8V output to 3.3V output)

[Selamu]

Hi community,

We use a PCA9420 PMIC on our design and would like to change BUCK2 (SW2, system buck regulator) default 1.8V output to 3.3V. I checked the datasheet and it shows that, on page 15, the SW2 output voltage can be programmed via I2C register from 1.5V to 2.1V, or from 2.7V to 3.3V in both at 25mV/step, but the maximum voltage which is available to select on all mode settings is 2.1V.

anybody has an idea on how it will be changed to 3.3V?

Regards

[TomasVaverka · Accepted solution]

Hi Selamu,

In order to set SW2 output voltage in the range of 2.7V to 3.3V, the SW2_OUT_1_OFFSET bit needs to be set to 1:

Then SW2 Output Voltage = SW2_OUT_1_LSB[4:0] + 1.2V, so if you set SW2_OUT_1_LSB[4:0] = 0b11001-0b11111 = 2.1V, then SW2 = 2.1V + 1.2V = 3.3V

Best regards,

Tomas