nRF52820 Beacon cannot update UUID/Major values below 2.8V in nRF Connect for Mobile

[daiki45064]

Hello Nordic team,

we are using a nRF52820 module in a beacon. After flashing the firmware and connecting via nRF Connect for Mobile, we can read the Service and Characteristic list. However, performing a write operation fails when the supply voltage is below 2.8V.

We have confirmed that this issue occurs when the supply voltage is below 2.8V.
When powered above 2.8V, configuration changes work normally.

Could you please advise if there is any known voltage threshold or internal limitation in nRF52820 that prevents writing configuration data below 2.8V?
Or could this be related to flash write operation voltage levels?

Additional Information:

• nRF52820 module

• Firmware: Custom beacon firmware based on SDK 2.5.0

• Supply voltage: 1.8–3.0V (problem occurs below 2.8V)

• Tool: nRF Connect for Mobile (iOS/Android version)

Thank you in advance for your support.

[Hieu]

Hello daiki45064,

Could you please let me know:

• Are you working with a custom board?
  • If so, could you please share the schematic?
• How are you providing power to the test board?
• How are you providing the supply voltage to the board
• With how many physical units have you observed this issue?
• What are the steps you have taken to produce with issue? In particular, I want to know how the voltage was changed and provided.

Hieu