Jinx, that sounds good but I need 5.0volts.

This is an mpu circuit, so I use a diode to drop off .7v, then when the mpu
sees the battery voltage has dropped to around 5.75v, the mpu turns on a
mosfet that shunts the diode. This would also be a good time to signal a low
battery condition. Would I need an n or p channel mosfet to shunt the diode
from the battery plus post, and what signal, high or low?


----- Original Message -----
From: "Jinx" <joecolquitt@clear.net.nz>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Sunday, December 19, 2004 1:10 PM
Subject: Re: [EE:] Is this going to die?


> John, can you jack up reference pin with a diode instead ?
> This will give you an o/p V of 5V+diode and allow you to use
> a 9V battery as the i/p limit has also been raised by a diode V
>
> This is something I do with zeners (k to pin, a to 0V) or trimpot
> to raise o/p to non-standard voltages. With a zener you need to
> have a couple of mA back from the o/p to the cathode to stabilise
> it, but I "think" you can insert a signal diode (eg 1N4148) in the
> reference pin path to ground, with cathode to 0V and anode to
> pin without needing any feedback as above. This would give you
> an o/p voltage of ~ 5.6V and an i/p range up to 9.6V
>
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