Pages: [1]   Go Down
Author Topic: Op amp output as digital input  (Read 661 times)
0 Members and 1 Guest are viewing this topic.
India
Offline Offline
Full Member
***
Karma: 0
Posts: 176
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi,
I am planning to provide a 5V output of an op amp directly to a digital pin as input to Arduino Mega. Is there any chance of damaging the board?
Logged

Massachusetts, USA
Offline Offline
Tesla Member
***
Karma: 208
Posts: 8822
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

As long as the voltage is limited to the range 0 to 5V it will not harm the Arduino.
Logged

Send Bitcoin tips to: 1L3CTDoTgrXNA5WyF77uWqt4gUdye9mezN
Send Litecoin tips to : LVtpaq6JgJAZwvnVq3ftVeHafWkcpmuR1e

India
Offline Offline
Full Member
***
Karma: 0
Posts: 176
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks. One more question. If i supply 5V to the output pin of an op amp, will it damage the op amp?
Logged

Offline Offline
Edison Member
*
Karma: 5
Posts: 1730
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Depends on the opamp, if the 5v is coming from an arduino output you may fry the arduino pin first, depends onthe actual opamp, you couldn't go wrong with a 220 -1kohm resistor in between, you'll never have a problem then so long as the opamp doesn't go above 5v, and then a 5.1v zener would fix that
Logged

Offline Offline
Edison Member
*
Karma: 116
Posts: 2205
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
If i supply 5V to the output pin of an op amp, will it damage the op amp?

Depending on the opamp, but generally no for small signal opamps and potentially yes for power opamps.
Logged

Massachusetts, USA
Offline Offline
Tesla Member
***
Karma: 208
Posts: 8822
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I suspect that if you connect the output directly to the 5V supply and the output is trying to drive LOW (0V) you will probably damage the output transistors of the op-amp.  

If you connect through a pull-up resistors you might be OK.  Depends on how much current the op-amp can source or sink and how much current will flow through your pull-up.  A 1K resistor (5 mA current) might be safe.  Depends on your op-amp.
Logged

Send Bitcoin tips to: 1L3CTDoTgrXNA5WyF77uWqt4gUdye9mezN
Send Litecoin tips to : LVtpaq6JgJAZwvnVq3ftVeHafWkcpmuR1e

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 620
Posts: 33999
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
If i supply 5V to the output pin of an op amp
This begs the question as to why on earth you would want to apply a 5V power line to an output. Connecting outputs direct to a supply makes no sense. What are you trying to do?
Logged

Pages: [1]   Go Up
Jump to: