1
\$\begingroup\$

I'm studying reference design from TI (pdf).This design shows the solenoid control circuit. I was interested, why a differential amplifier is used to measure the current? Why not use non-inverting circuit op-amp?

enter image description here

| improve this question | | | | |
\$\endgroup\$
0
\$\begingroup\$

A differential input with Kelvin connection from shunt to amplifier will reject noise much more effectively than a single-ended input. I think this is the main reason. If it were single ended, some common mode noise might couple onto the trace. With differential pair routing, noise will most likely couple onto both traces equally and be rejected by the amplifier.

| improve this answer | | | | |
\$\endgroup\$
0
\$\begingroup\$

Because high currents flowing through the sensor resistor may flow to the GND pin of the opamp, and induce measurement errors.

| improve this answer | | | | |
\$\endgroup\$
  • \$\begingroup\$ Because of GND R34 and GND U2A can have different potentials. Did I understand you correctly? \$\endgroup\$ – AndreyB Oct 1 '17 at 17:50
  • \$\begingroup\$ Close. GND R43 and GND R7 can have different potentials. \$\endgroup\$ – analogsystemsrf Oct 1 '17 at 23:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.