Dear sir,
I have power supply with several outputs, I wish to test these outputs each one independent regards to the others.
I want to use INA220 to measure Vbus / Current (one INA220 for each output).
1. for current sense do I have to connect the ground or can it float ?
2. do you have any idea (or other IC) for measure the floating voltage ?
Thank you !
Yariv
Yariv,
The ground of the IC must be connected in both cases because the IC requires a reference with which to compare the measured voltages. The ideal way to do this would be to place the INA220 on the secondary side of the power supply and pass the digital data back to the primary side using an isolated digital transceiver, this would be floating the INA220 in a sense. TI will be releasing a digital isolator compatible with the two wire serial interface used on the INA220 very soon, however we are able to deliver samples of this part now if you are interested. I should also mention that the AMC1200 is an isolated current shunt amplifier that can be used to perform isolated current measurements, however it would need to be paired with a suitable data converter.
John Caldwell
Analog Applications Engineer
PA Linear Apps