Abnormal low-power current

[sean]

Hi，

    The same hardware and software have been in continuous production for several years without issues. However, the latest batch exhibited abnormally high power consumption.

During software debugging, an anomaly was detected on the GPIO14 pin:

• High output → High power consumption.

• Low output → Normal power consumption (tested with 2x 52805 units).

Key Findings:

1. Hardware Design: GPIO14 was not physically connected in the actual circuit.

2. Software Behavior: The firmware drives GPIO14 high/low as an indicator of the module’s low-power state.

3. Post-Test Observation: Subsequent impedance measurements of GPIO14 revealed irregularities.

Question 1: Unused IO，I see it defaults to input status。How to properly handle unused IO of the product under low power consumption conditions

Question 2:Do you have any suggestions for the phenomenon described above

[Kenneth]

Hi,

My recommendations is to check the PIN_CNF[] register:
https://docs.nordicsemi.com/bundle/ps_nrf52805/page/gpio.html#register.PIN_CNF-0-31

If the INPUT field is Connect, then the pin must be connected physically to a defined logic level (e.g. it can be connected to gnd, vdd, pull-up, pull-down or otherwise have some external circuitry that ensure the pin is in a low (<0.3*VDD) or high state (>0.7*VDD)).

If the INPUT field is Disconnect, then it doesn't matter if the pin is connected to a logic level or not.

Let me know if I should transfer this case to Nordic QA for failure analysis.

Kenneth