Enabling DC/DC converter for REG0 stage nRF52840

[OnurGules]

Hello,

We have a custom design board using Raytac MDBT50Q-1MV2. We'd like to use the DC/DC regulator for REG0 stage for low power consumption. Please see the relevant part from our schematic, which was also approved by Raytac.

When I try to enable DCDC for REG0, the device hangs, and I have to do 

nrfjprog --recover

to recover the device. I use this code to setup DCDCEN, DCDCEN0 and REGOUT0:

    if (NRF_UICR->REGOUT0 != UICR_REGOUT0_VOUT_3V0)
    {
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
        NRF_UICR->REGOUT0 = UICR_REGOUT0_VOUT_3V0;

        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

        NVIC_SystemReset();
    }

    NRF_POWER->DCDCEN = 1;

    NRF_POWER->DCDCEN0 = 1;

If I don't enable DCDCEN0, the device works. We supply the device with 2xhalf aa 3.6v batteries, and we require 3.0v for the peripherals to run correctly.

Can you please help us find out what the issue might be?

Kind Regards,

Onur Gules.

[Jared]

Hi there,

• How many samples are you seeing this issue on? What percentage?
• I can't tell from the snippet of the schematic that you've shared, but did you remember to include all of the decoupling capacitors? More specifically, the reference design for the module specifies 10 µF capacitors on both the VDD(28) and VDDH(30).

regards

Jared  

[OnurGules]

Hi Jared,

I tested two devices and they both have the issue. I think you might be right with the capacitor on VDDH. I am not a hardware person so I asked our hardware guys to take a look. I'll post updates here.

Regards,

Onur.

[Jared]

Hi,

Ok, keep me updated.

regards

Jared