ADC protection and amplification circuit

[hospodar]

Posted on April 29, 2013 at 09:24

Hello, 

I need circuit, which will be protect ADC input against overvoltage. Also, it should amplification low-level voltage (from sensor for example). Do you have something like this?

Thank you.

[frankmeyer9]

Posted on April 29, 2013 at 11:09

For smaller voltages, a series resistor and a zener diode of 3.3 ... 3.6V (or better two in antiparallel configuration), would serve well.

For environments with high EMI load and surges of hundreds of volts (say, inductive loads with large back - EMF), you might need special parts like VDRs or suppressor diodes.

After all, you might need to have some expectation about the level, duration and frequency of your events the ADC needs to be protected from.

[hospodar]

Posted on April 30, 2013 at 17:43

Can I use operational amplifier with adjustable gain (for low-level signals) followed by voltage follower (for limiting high-level signals)? If I will be sure that input signal isn´t low-level, I connect this signal directly to voltage follower.

[raptorhal2]

Posted on April 30, 2013 at 18:46

The voltage follower isn't necessary if the op amp reference voltage is the same as the processor.

Cheers, Hal