Secure DFU bootloader power consumption

[acanidio]

Hi everyone,

I'm developing a new application/product. It will feature a nRF52805 without the LFXTAL but with DC/DC support. I'm
developing with the NRF5 17.0.2 SDK.

I compiled the secure_bootloader example to understand its current consumption. Its power consumption is around
580 uA with peaks of around 20mA.

I know that i can improve power consumption tweaking advertising and eventually connection parameters (those last
are not advised since i want to maximize throughput), but this is not my primary concern for now.

I have threen questions:

• Is this power consumption correct from Nordic point of view?
• From my experience when DC/DC is enabled the power consumption peaks are around 15mA. Is there any
  configuration in sdk_config.h to enable DC/DC?
• What other strategies can be used to further improve power consumption?

Best regards,

Andrea

[Einar Thorsrud]

Hi Andrea,

Is this power consumption correct from Nordic point of view?

If this is the idle current consumption in the bootloader, then it is higher than expected. See for instance this thread.

From my experience when DC/DC is enabled the power consumption peaks are around 15mA. Is there any
configuration in sdk_config.h to enable DC/DC?

No. But you can enable the DC/DC by either calling NRF_POWER->DCDCEN = 1 before enabling the SoftDevice or sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE) after enabling the SoftDevice. That will reduce the peak currents. So the simplest way to use the DC/DC in the bootladoer is to write to NRF_POWER->DCDCEN in the beginning of the main function in examples\dfu\secure_bootloader\main.c.

What other strategies can be used to further improve power consumption?

First you we need to know why you see such a high current consumption. Have you ruled out that it could be caused by other component on your board? could it be some GPIO's that should be configured in a specific state also in the bootloader to not cause high current consumption via some external components on the board etc?

Also, while it is always good to understand the detail of your product, high current consumption in itself is typically not a big problem in the bootloader, as a device typically very rarely enters DFU mode. And when it does, it is typically only there for a minute or less.

Einar