I'am trying to match 0.5-1.05 volt sensor output using a single supply opamp 
to a 0.05-3volt references.. the 0.05trim is to acount for the opamp output 
not being able to swing exactly to the voltage level on its powerrails.. 
i.e. I'm using a virtual ground..

> Your VCC is probably at least that accurate.

I dont want to waste a2d counts as I need to have good A2D resolution so I 
cant exactly use the VCc as a reference. If I simply use 0-1volt sensor 
output and amplfy it to 0-5volts.. I would be losing counts and will not be 
able to detect voltages close to 5volts and 0volts as I know of no opamp 
that can swing to their rail voltages.. even those rail-rail opamps cant do 
that..

thanks..

"David VanHorn" <dvanhorn@microbrix.com> wrote in message 
news:25b178740610031250n66006c55u996ef14d8d1bbc67@mail.gmail.com...
> On 10/3/06, genome <jtroxas@gmail.com> wrote:
>>
>> hello,
>> Anybody can recommend 3 volt Vref Diode.. I cant use a 2.5volt such as
>> LM336BZ-2.5 as the datasheet for pic18f242 says:
>> (VREFH - VREFL) must be minimum of 3V when Vdd >= 3V..
>> is this correct as I've heard on other PICS its 2.5volts.. maybe I could
>> use
>> a zener but unfortunately I could not find any zeners here that has 1%
>> tolerance..
>
>
> Your VCC is probably at least that accurate.
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