nrf52832 1.8v, external and internal dc/dc

[silvergaucho]

Hei guys,

for a new custom board based on nrf52832 where i have to minimize power:

• have an external Li-Po battery, with a cutoff @3.0v, so the range will be 4.2v-3.0v
• want to bring Vdd to fixed 1.8v via an external DCDC ( it will supply power to all the Vddio lines around the board, so i needed anyway).
• I read around that using the internal DCDC, with two additionals inductances, could save power even more using a sort of internal switching between internal DCDC and LDO. I have space for those inductances.

So, am i wrong implementing 1.8v extrernally and have a conf with the two external components?

Thanks a lot

[Stefan Birnir Sverrisson]

Hi

Yes, you cant supply nRF5x with more than 3.6V, so you would need an external LDO or DCDC to lower the voltage of the Li-Po battery to an acceptable level. Perhaps a good external DCDC is mentioned here

A DCDC will waste less energy than LDO when lowering voltage from input to output. The drawback is that DCDC uses current in order operate, and is therefore not more efficient than LDO when load current is low. For the production version of the nRF52832, the internal DCDC is automatically turned off when using LDO is more efficient than using DCDC.

So, even if you use external DCDC to lower voltage to DCDC, you will have further power savings with enabling the internal DCDC as well.

[embedded717]

Is there 1.8V available in these boards ? I am using 52840, I see 5V and 3.0V. But I need 1.8V, I am hoping I wont have to use external LDO board for 1.8 V and 3.3V that I need for my sensor.