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Connecting ADC input to microcontroller and ground

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Full Member level 1
Apr 21, 2006
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iam using In build ADC Atmega32 controller

iam using 0-10V signal to ADC input of the controller by using fixed resistor

voltage divider(10V to 5v).

what precation i have take for ADC input PIN from high voltage ,means

if volatge comes more then 5V .

What ground I have to connect for sensor signal (-ve) and volatage divider

ground either digital ground or analog ground

What precautions I have to take while connecting analog signal to the micro

controllers(In build ADC ).



Re: ADC ground

What about this, maybe someone else could comment if it's not a good way to go anyway..

Put a Zener diode with a 10v breakdown on the input where the signal comes in to limit any transients/overvoltage.
I’m not sure how frequently the input may be overvoltage(and by how much) so wont comment of the power rating of the zener.
This way the voltage divider will never be subject to anything over 10v and therefore the ADC input will never go over 5 volts. Sound ok ?

For grounding I’m thinking that it would be ok to tie the voltage divider and sensor ground to a common analogue ground.
The important thing is that your ADC power and ground are very clean and filtered well.
As a good rule of thumb if not using ground plains use star point grounding, one for sensor and one for divider to be super clean but I think
That’s probably way over the top.

Re: ADC ground

using a zener is a good solution... or u can go for clippers also....

Re: ADC ground

Why not use 5v6 zener instead 10V? Voltage value more than 5V is not happy tollerate by ATmega32... (aftrer partitor...). This is useful for other microcontroller line protection

ADC ground

Check to see if the ATMEL chip has built in clamp diodes on that input. All PICs have them built in on all but the MCLR pin.

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