RE: nrf52840 Dongle burning out - Running 3V on VBUS, drawing 60mA

nordicnoob — Wed, 31 Mar 2021 18:26:38 GMT

Thanks for the extremely quick response!

Since I am using 2 1.5V batteries in series as my power source, can I instead power the dongle by cutting SB2, soldering SB1, and powering using the VDDOUT pin? The range of 2.5-3V seems to be in an acceptable range here is it not?

If I were to, for example, use the Blinky BLE peripheral firmware example, would I need to change any registers for this to work? Or, can I simply use the s140 7.01 soft device as is when powered using 2.5-3V into VDD? Is special handling only required only for VDDH (ie inputs from 3.6-5.5V)?

RE: nrf52840 Dongle burning out - Running 3V on VBUS, drawing 60mA

Simonr — Wed, 31 Mar 2021 12:31:06 GMT

Can you provide some details as to how you're powering the dongles exactly? 60mA is incredibly high, and is likely due to you supplying the VBUS with too low of a voltage. As stated in the USB supply section of the nRF52840 PS you need to use a 5V supply when using the USB peripheral, as an internal voltage regulator is used to convert the VBUS supply to 3.3V. When using a supply lower than 5V that might damage the USB peripheral I'm afraid.

Best regards,

Simon