# (1 mV - 800 mV) to (0 - 2.5 V)Voltage

#### kunal burman

Joined Nov 2, 2018
13
Hello I am looking to amplify my signal from (1 mV - 800 mV) to (0 - 2.5 V) Voltage, So that I can read it using ADS127L01!
Application: I am using a current source of 1mA- 1A and measure the voltage drop between (1 mV - 1000 mV). This voltage then i need to read using ADS127L01. Please can anyone guide me with the same?
Regards,
Kunal

#### Ian0

Joined Aug 7, 2020
9,469
You need a current shunt amplifier such as AD8418, INA180 or INA181, but they have fixed gains of 20, so reduce your shunt resistor to 0.125Ω, which will also reduce its power dissipation by a factor of 8.
If your current flow is bidirectional, the AD8418 is ideal because you can bias the zero current output to half the supply voltage.

#### Irving

Joined Jan 30, 2016
3,792
Hello I am looking to amplify my signal from (1 mV - 800 mV) to (0 - 2.5 V) Voltage, So that I can read it using ADS127L01!
Application: I am using a current source of 1mA- 1A and measure the voltage drop between (1 mV - 1000 mV). This voltage then i need to read using ADS127L01. Please can anyone guide me with the same?
Regards,
Kunal
So is your upper limit 800mV or 1000mV? Either way you need a gain of either 2.5/0.8 or 2.5/1 = 3.125 or 2.5 with a very low <a few uV offset and low noise. Suggest an instrumentation amplifier, but need to know other info to make recommendation eg, high side or low side, available supply rails,and an outline schematic would help. Also frequency response/sample rate.

Other considerations:

Why 24bits? That's 140nV resolution... but with noise in system (bandwidth dependent) you won't get close to that so pointless.

How are you sampling current - 1ohm resistor? How will you compensate for resistance change with temperature?

Edit: I agree with @Ian0 's suggestions, but above points still valid as are many other issues... would help if you explained overall purpose and reason for wide range...