Power On Reset doesn't work

[Genyu]

I found a problem of the nRF51822 in boot state.

Power on reset is not executed occasionally when used dying battery.

The problem occurs in the following steps:

1. Connect the dying CP2032 around 2.85 [V].
2. Remove it.
3. Reconnect it when VDD-GND voltage of the board is 0.4 [V] ~ 0.5 [V].
4. main function is not executed, the state of being in SYSTEM OFF MODE.

Frequency of occurrence is about once in 10 times.

My environment is as follows:

• nRF51822 Revision3
• SDK10.0.0
• SoftDevice S110 Ver8.0.0
• FW : ble_app_beacon (sample application)
• Custom board

Circuit configuration

• Bypass capacitor (0.1uF) is connected to the nRF51822.
• The capacitor (10uF) is connected to power line of board.
• Power supply IC is not used.

Is there any conditions that power on reset is not executed?

[Øyvind Karlsen]

Hi,

We need more information that would allow us to find exact cause, please create a case on My Page https://www.nordicsemi.com/eng/nordic/mypage and add the following details:

• Schematic and layout.
• A description of test setup.
• Frequency of occurrence and build code.
• Analog capture of VDD, nRESET, DEC1 and DEC2.

Best regards,

Øyvind

[Nick]

Just curious if you have found a resolution to your issue or any more info on what caused it? I am seeing a similar issue when a battery approaches 2.8v, sometimes it never powers on again...

[Øyvind Karlsen]

Hi,

Are you pulling a lot of current from small batteries? This will cause the voltage to drop, triggering a power on reset. With some coin cell batteries the voltage will never recover if they are pulled too hard.

If that's not what you are seeing, please follow the guidelines in the answer below.

[little boy]

may be your circut has some problem when power on.check the pin "SWDIO/nRESET" when power on.if circuit doesn't Expected volatility，and it will cause repeat reset.