DC/DC ON

[Dan Colob]

I see that there is a significant drop in average current with DC/DC on, will this also be true if I already have a 3V from a BMS (with its own DC/DC) supplying to Vdd (won't connect to Vddh) and then having the DC/DC of the nrf on to give 3V?

[Turbo J]

Dan Colob said:

(won't connect to Vddh)

Careful: VDDH needs to be connected to VDD if REG0 is not used.

There are two DC/DC regulators on the NRF52840. One (optional) for VDDH -to- VDD regulation, and one for internal voltage (1.3V VCore). Most of the chip internals run on VCore, and thus benefit from the latter DCDC running in switching mode.

[Dan Colob]

I am going to be using the radio and this thread (https://devzone.nordicsemi.com/f/nordic-q-a/2950/antenna-in-20mm-circle-pcb) mentions the internal DCDC causes noise on TX, RX so if I have 3 and even tho the DCDC will be more efficient to turn down to 1.3V, I think I might just have to use LDO

Would you know how I can calculate how much power I could save if I feed in 1.8V to the nrf and use the LDO v 3V and use LDO?

[Andreas]

Hi,

 

Sorry, but I am not sure I understand. In your first post you refer to 'VDDH', which is a pin on the 5V compliant nRF52 devices we have (nRF52840, nRF52833, nRF52820). The post you link to is specific to nRF51 though, which is a vastly different device (in this context). Can you confirm which you are using?

For nRF52 series we have the Online Power Profiler, which you can use to calculate average current consumption for various BLE scenarios, taking into account various settings and nRF52 part. Also note that the spur issues mentioned do not apply to nRF52 series.

nRF51 is unfortunately not added to the Online Power Profiler, there are however some resources on Devzone (e.g. here) that you can use.

 

If you are doing anything proprietary, not BLE, we unfortunately do not have any such tools, you will have to profile and calculate manually. As for difference in active current consumption (DCDC vs LDO) can be found in the respective datasheets, under electrical specs for CPU and radio.

 

Best regards,

Andreas