nRF52833 Power Scheme

[harrykuang]

Hello,

For us our IO rail is 1.8V. In this case do you see a big difference in power consumption whether REG1 is in LDO mode or DCDC mode? From 1.8V to 1.3V if in LDO mode the efficiency is about 72% best case. In DCDC mode I don’t see any efficiency plots or a quiescent current in the datasheet (maybe I am just not looking in the right place). But I am thinking it is probably 85% or so. Does this sound about right ? I don't see any significant advantage to using the DCDC for REG1 unless the nRF is in HV mode where the output of LDO0 is much higher than 1.8V.

Harry

[Martin Sivertsen]

Hi Harry,

Am I correct in assuming you have VDD = 1.8?

Have you configured the nRF52833 to use high voltage mode (REG0) or normal voltage mode?

Best regards,

Martin S.

[harrykuang]

Hi Martin,

Yes VDD = 1.8V since that is our IO system IO voltage level. REG0 is in normal voltage mode. In terms of HW VDD and VDDH are connected on the nRF.

Harry

[Martin Sivertsen]

Hello Harry,

We do not usually share DCDC efficiency plots since they can be more confusing than clarifying since the power and clock system automatically turns on and off resources based on peripherals and power modes.

What we usually do is to give 1:1 comparison between LDO and DCDC mode for different use cases (e.g. TX 8 dBm, TX 0 dBm, CPU running Coremark, RX BLE1M).

For example: At TX 8 dBm (only Radio) we get  ~26 mA with DCDC and ~30 mA with LDO at 1.7 volt. At 3.0 volt the numbers are ~14 mA and 30 mA so the statement is correct, higher difference between input voltage and output voltage will give better efficiency advantage for DCDC.

I hope this is somewhat clarifying, we can get more data (comparison values) for you if you need.

Best regards,

Martin S.