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Re: Just to verify my reset circuit

Subject: Re: Just to verify my reset circuit
From: "Chris"
Date: 10 Apr 2006 07:18:55 -0700
Newsgroups: sci.electronics.basics
Ant_Magma wrote:
> My reset pin is active low, this would work right?
>
> Vcc
> |-------
> |      |
> |      -
> R10k 1N4148
> |      +
> |      |
> |-------To reset pin
> |
> C10uF
> |
> |
> GND

Hi, Ant.  It depends.  You have to look at the data sheet to see if a
very slow-rise reset is OK for your chip.  This will take dozens of
milliseconds to go through the intermediate area between logic "0" and
logic "1", which might be a problem for the reset circuitry internal to
your chip.  Look on the data sheet for maximum reset pulse rise and
fall times.

If it is a problem, or if you're not sure, and you have a spare
inverter gate and no time to research, it might be just best to reverse
the R and C, and then use the inverter to square it up anyway.  No
points off here.  The hysteresis of a 74HC14 can be invaluable for
this.  If I need an inverter on a board, I'll spec one of these so I
can have this squaring up capability.

Good luck with your project.  I hope things are going well.

Chris


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