My customer has a board in witch 2 of the op-amps in LMV344I perform voltage amplification of 2 current sense resistors.After replacing one of the shunts, the performance of one of the op-amps has worsened: with zero voltage on the shunt, the amplifier output voltage changed from 30mV to 700mV.
After replacing the LMV344I, the opamp output offset returned to a normal value. Changing another time the same shunt resistor give the same problem, with different op-amp output offset.
The 2 input of op-amp are conneted with the shunt through two 5K6 ohm resistors. Could it be a problem due to the welder ? An if so, why soldering a LMV344I with the same welder doesn't produce offset degradation ?
Anyone has an explanation?
