INA 826

Hello Paddy,

What is the common-mode voltage of your sensor? Also, what is your supply voltage?

Hi Pete,

Supply voltage of sensor is 2.4 V and max supply available on board is 24 V. 

I am using Wheatstone bridge configuration for detection of signal. 

Thanks,

Paddy

Hello Paddy,

Thanks for the additional information. I will assume that the common-mode voltage of the sensor is ~1/2 the supply voltage. I will also assume that you're going to regulate the supply voltage from 24V to 5V for the INA826. This would make sense if the INA826 is interfacing with a device that requires a 0V-5V signal (I assume you don't want the INA826 to be able to output enough voltage to damage the device it's connected to).

That said, please be aware of the output swing of the INA826 (or just about any instrumentation amplifier for that matter). The output swing depends on the supply voltage of the device, the reference voltage, gain, and the input common-mode voltage.

For your case (Vicm=1.2V, Vs=5V, Vref=0V), I would expect an output swing of 100mV to ~2.75V or ~3.75V depending on gain (please see figures 11 and 12 in the data sheet).

If that range is acceptable, I see no reason why the INA826 couldn't be used in your system. If you need a larger output range, there are a couple options. First, you could genreate a negative supply voltage and power the INA with dual supplies (e.g. +/-5V). Now your output can swing according to Figure 14. Please note a common-mode of 1.2V is close to the voltage where the output swing starts to decrease as shown in Figure 14.

Another option would be to evaluate the INA326. It has a unique topology that allows it to have a rail-to-rail output independent of input common-mode voltage. One drawback may be the device's bandwidth.

Finally, some of our current shunt monitors may be of interest. Please take a look at the INA210-4 family and INA282-6 family. One drawback is that these devices have a fixed gain.

Hi Pete,

Thank you very much for your suggestions!!!!

I have seen the term Common mode voltage of sensor in your post. I really appreciate if you explain me what it exactly means?  

Also suggest which is most suitable INA 826 or INA 326??

Thanks,

Paddy

Hello Paddy,

Please see attached slide.

I would suggest the INA326, however, the device is sensitive to capacitance on pins 1 and 8. Therefore it is not conducive to prototyping on a breadboard. I suggest laying out a PCB.

Hi Pete,

Thank you very much for your guidance and giving your precious time.

Please have a look on attached circuit. I am getting  25mV  at the output when input is zero.

I have used single supply of 5 V. It looks good when I use ± 5 V supply.

But max.  dual supply range mentioned is ± 2.5 V.

Please suggest what I need to do to get the output ~ 0 when there is no input present.

Thanks a lot!!!!!!

Regards,

Paddy