Hello team,
I have a question for INA849 use case.
Of course, I understood INA849 is an instrumentation amplifier and it should be used for differential input, but is it also an acceptable to be used with single-end input such for an audio microphone despite losing some performance benefits (e.g. CMRR)?
If yes, is there a reference design example for a single-end use case?
Thanks in advance.
S.Sawamoto
Hi Shinya,
Thanks for your post. I can help you.
You can use the INA849 single-ended, by grounding one of the inputs. You just want to make sure the voltages seen at the inputs are within the input common mode voltage (VCM) range of the amplifier. For the INA849, the VCM range is 2.5V from either power supply rail. If you have +/-15V supplies, that means the voltages seen at IN+ and IN- need to be between -12.5V to +12.5V. So if you need to ground one of the inputs, the negative supply rail needs to be at least -2.5V.
Here is a quick example I put together. The supplies are +/-15V. The ref is set to mid-supply = ground. The gain is 1V/V. I put 5V on IN+ and 0V on IN-. The output of the INA849 is VOUT = gain * differential voltage + ref = 1V/V * 5V + 0V = 5V:
