From: Mike Rigby-Jones <pic.developer@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 21 Apr 2020 06:59:49 -0700
Subject: Re: [EE] LDO reg keeps failing. Looking for suggestions.
Thread-Topic: [EE] LDO reg keeps failing. Looking for suggestions.
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The problem is not Vout rising, but rather Vin falling below Vout (which is
held up through decoupling capacitance) due to current transients etc.

I would have D8 cathode connected to the input pin of the regulator
however. As drawn a dip in the supply rail could cause the micro to brown
out, negating the usefulness of the input diode.

Mike

On Tue, 21 Apr 2020, 08:32 Sean Breheny, <shb7@cornell.edu> wrote:

> On Mon, Apr 20, 2020 at 9:33 PM David Van Horn <
> david.vanhorn@backcountryaccess.com> wrote:
>
> > I disagree.
> > The failure mechanism is well documented, where Vout > Vin.
> > The point of D8 is to prevent the input pin from being more than a diod=
e
> > drop below Vout in that situation.
> > But the problem mechanism here isn't Vin falling, it's Vout rising.
> >
> > Why do you say that the problem is Vout rising? It appears to me that
> Vout
> only powers the microcontroller, not the motors. Any regeneration from th=
e
> motors should go directly into the battery.
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