The issues when LTC6362 was used as differential amplifier

Hello,

what input voltages are applied in that case?.

If no current is flowing, the differential input voltage is 0V, but still a common mode input voltage is applied. Is this inside the allowed input common mode voltage range? (It should range approximately from -1V to +4,xV in your case.)

If you exeed the allowed range, the chip may deliver strange results.

best regards

Achim

The shunt resistor is connected below fig, so I think the common mode voltage will be close to 0V.

Is there no problem with the circuit?

In addition, almost 0V is applied to C72 capacitor voltage

Hello,

if the shunt resistor is connected to GND, the input common mode voltage is OK.

Then I do not see any obvious problem in the schematic. If it does not work as expected I would first measure the voltages directly at each pin of the chip to check, if the pcb really is connected as the schematic shows (soldering problem or something similar).

best regards

Achim

It was confirmed that the 1.5V ref voltage sometimes shakes or rises to about 2.7V when LTC6362 is attached. In this regard, do we need to do anything additional to the Vocm pin?

If LTC6362 is not attached, 1.5V works well.

Hi dsazxc ,

Sorry for missing this thread. Can you try directly using a 1.5 V supply to the Vocm? If the LTC6362 works fine, I think there is a problem with the connection between the reference source and the LTC6362, which could cause the issue. Thank you.

Regards,

Gilbeys