Brown-out and POR not 100% failsafe?

RE: Brown-out and POR not 100% failsafe?

jbouchat — Fri, 16 Dec 2016 15:01:25 GMT

Hello, Is it possible to have an update regarding this topic? Does Nordic approve the solution to replace the 10K pull-up by 1meg pull-down on SWDIO/nRESET?

RE: Brown-out and POR not 100% failsafe?

Reinier Gerritsen — Mon, 30 May 2016 08:26:33 GMT

Thanks Konstantin! I replaced the 12K pull-up for a 1M pull-down. As far as I can see this solves the problem. The increased power supply is no problem at all, we don't use batteries in this application. I got the same advice from M6 (the original poster) who happens to be a former co-worker!

RE: Brown-out and POR not 100% failsafe?

kchuva — Sat, 28 May 2016 09:25:54 GMT

Hi, Reinier, can you use a 1Mohm resistor between SWDIO/nRESET and GND? That will increase current consumption with VDD/1Mohm. This way solved our problem

RE: Brown-out and POR not 100% failsafe?

Reinier Gerritsen — Fri, 27 May 2016 14:46:21 GMT

Same issue here, when the power supply drops to the 0.5V region and then back to 3.3V, a power-on reset is not always initiated. When the device is in this faulty state, the power must first drop below 0.4V in order for the device to start normally again. NRF51822QFAAH0 (1544MG), no soft device.

RE: Brown-out and POR not 100% failsafe?

Kenneth — Tue, 05 Apr 2016 10:21:28 GMT

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.

RE: Brown-out and POR not 100% failsafe?

kchuva — Fri, 01 Apr 2016 14:36:09 GMT

I have the same problem and the same behaviour on my nRF51822 H0 revision. S110 SoftDevice is enabled. When the VCC drops to about 0.5 V and slow comes back to 3.0 V, the brown-out reset is not happenning. So, I can't establish connection to BLE device.

If VCC return to 3.0 V rapidly, than brown-out reset device successfully and connection to BLE device is established.

I don't think when this happens the flash is corrupted, because after full power reset the firmware is started correctly.

Does brown-out must always reset the MCU when VCC drops below 1.7 V?

Are there any known problems with reset?

Can the slew rate of the voltage or the time spent at low levels affect on the reset system?