Manual manipulation on DC/DC and LDO regulators

[grabro]

Hi,

We are trying to investigate the interval noises of our custom developed sensor board with a digital accelerometer (With SPI interface).

After checking the software and hardware configurations, we believe that the problem is caused by the VDD voltage spikes of the accelerometer.

I am aware that by calling sd_power_dcdc0_mode_set(NRF_POWER_DCDC_ENABLE) and sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE), the nRF chip will automatically take care in optimising the power efficiency between DC/DC regulator and LDO. But is there a way to manually operate the power mode of the nRF chip? For example, keep the system to operate in DC/DC regulator instead of switching to LDO.

Additional note 1: We are using a custom board with nRF52840, with mounted inductor.

Additional note 2: By checking the power profile and NRF_POWER->DCDCEN, I can confirm that the DC/DC regulator mode can be triggered successfully.

[haakonsh]

After checking the software and hardware configurations, we believe that the problem is caused by the VDD voltage spikes of the accelerometer.

 I suggest you isolate the accellerometer's power supply and scope it in order to verify it. 

But is there a way to manually operate the power mode of the nRF chip?

 Why do you need to turn on/off the DCDC regulators? What problem are you trying to solve? 

Can you share any scopes of the noise?