nRF52832 Supply rise time

RE: nRF52832 Supply rise time

butch — Wed, 21 Sep 2016 10:03:27 GMT

OK, now I understand. Just as a matter of interest, do you think this is a flaw in the product (in its voltage monitor circuitry), i.e. in your experience is it typical of other mcu's to reset on steps increases in the valid supply range? Also, would an external voltage monitor chip deal with step increases without resetting?

RE: nRF52832 Supply rise time

a.wallwitz — Tue, 20 Sep 2016 19:58:57 GMT

18.6.1 of the product specification states: "A step increase in supply voltage of 300 mV or more, with rise time of 300 ms or less, within the valid supply range, may result in a system reset." Which I want to prevent while switching from battery (2.0V) to external power supply (3.5V).

So this is not a side effect ;)

Due to the fact that I'm running of battery until the external PS is being used, will limit the bottom limit of Vcc to 2.0V. So I will not rise from 0V when I'm already running. The only problem I see is the initial startup of the device.

RE: nRF52832 Supply rise time

butch — Tue, 20 Sep 2016 17:58:35 GMT

Why would a smoothed rise time "prevent POR?" I suppose you mean a filter that has the undesired side effect of slowing the rise time? Is your external power supply noisy? In my experience with slow rise times from a solar cell power supply, a slow rise time can definitely prevent an mcu from resetting properly.