### Q

In order to do a precise current source of 1mA with the AD580, I need to knowthe resistance to add between pin "output" and "V-".

According to the formula witch is given I=2.5/R+1mA, the resistance must be as

large as possible.

What is the resistance value that I must add to have 1mA of current ?

What is the limit resistance value that I can put for the use as a current

limiter?

### A

You should use slightly higher than 1 mA.A 2.5Kohm resistor will give you a Current Source of 2mA.

For 1 mA , you will need a larger resistor , approx 5K, but this could

introduce noise, so you need to analyze the performance of your circuit with

respect to noise if you go higher.