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Vref and buffer

S

strider02

Jan 1, 1970
0
need to set the Vref in the ADC of ATmega16 and use some buffers to
the voltage to be measured. What should I use to produce a Vref of 5V,
7805 or some other ic is available for this purpose? And also should I
use opamp voltage follower circuit as buffer or some other ic?
 
A

Arlet

Jan 1, 1970
0
strider02 said:
need to set the Vref in the ADC of ATmega16 and use some buffers to
the voltage to be measured. What should I use to produce a Vref of 5V,
7805 or some other ic is available for this purpose? And also should I
use opamp voltage follower circuit as buffer or some other ic?

You can buy a 5V voltage reference (search digikey for "voltage
reference"), and hook it up to Vref (note the input voltage though).

You can also hook up Vcc to AVcc, and put a cap on Vref (if your Vcc is
stable enough)

Or, you can use the internal bandgap reference, if the measured voltage
is < 2.56 V (possibly through external attenuation).

You may not need an external buffer. Input leakage is < 50nA. If your
source can't handle that, you'll probably want a proper differential
ADC anyway.
 
R

Rene Tschaggelar

Jan 1, 1970
0
strider02 said:
need to set the Vref in the ADC of ATmega16 and use some buffers to
the voltage to be measured. What should I use to produce a Vref of 5V,
7805 or some other ic is available for this purpose? And also should I
use opamp voltage follower circuit as buffer or some other ic?

a 100 Ohms from the %v supply onto a 100nF cap.
As recommended by the manual

Rene
 
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