We have the same three board with same firmware using BMD350, two are consuming 63uA in sleep but one is consuming 4.5 mA, what could be the reason for higher current in the third board?

[vidit]

Hi Guys,

We have designed a custom board which is using BMD350.

Our application requires using the BMD350 in beacon mode and then going to sleep in low power.

We have written the firmware and fabricated 3 boards.

Following is how boards are consuming current,

1. When there is no firmware: 10 mA
2. When the firmware is there, in beacon state: 10- 12mA
3. When the firmware is there, in Sleep state: 63uA

Which is all fine, but there is one board, which is consuming 4.5 mA in sleep mode in place of 63uA, all three boards have exactly the same firmware.

We checked all components, all are fine. The board is also doing the work it should do in the active state, only the sleep current is different in this third board.

Did anyone face similar problems? What else can we check? Where could we be going wrong?

 

Thanks

[Stian Røed Hafskjold]

Things to check:

• Always power cycle after flashing
• Make sure that GPIOs are configured correctly. Most important:
  • If GPIOs are configured as inputs, and the input buffer is connected, the input voltage has to be either VDD or GND (and not floating). If it's floating use a pull-up or pull-down.
  • The same requirement usually goes for the inputs on external components. So make sure that the nRF52 GPIO output is configured correctly, not floating.
• You said you had checked all components. Not sure what you mean with "checked", but I would recommend replacing all components to see if some of them has failed. Especially the passive components, like decoupling caps.
• Put the chip to system off mode and measure the current. If it is still consuming high current I would suspect the problem to be external to the chip (or a damaged nRF52 sample). If the current goes down to normal sleep current, I would suspect that the problem lies with the FW.
• ESD damage. Sometimes the chips get ESD damaged (or damaged by applying a too high voltage, etc.). The symptom is very often high current draw.

So basically you have to narrow down the issue. First step would be to figure out if it's a FW issue or a HW issue, and if it's a HW issue, then figure out if the current is consumed by the nRF52 or other components.

A quick thing to try: If you have DCDC components populated on the board, you can try to measure current with and without the DCDC enabled. If you see a difference in consumption, then the current is probably consumed inside the nRF52 chip after the internal regulator, and then you have to debug the FW to see what goes wrong.