Hi Sir,
I am Wade from Pixart.
INA198 is used to measure current through our device power (5V).
but I found the abnormal voltage( at VIN+ = 3.3V, VIN- = 3.3V) when disconnect to device side and turn off supply power side ( = 0V) to VIN+ pin.
Why 3.3V has existed in INA198 ? no device no supply power.
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Our INA 198 design.
V+ pin = 5V,
OUT pin = connect to ADC IC
Shunt resistor RS = 100 ohm
VIN+ = VIN - pin to detect 5V
Device power = 5V
Hello Wade,
Thanks for considering to use Texas Instruments. So if I understand correctly you have the two conditions illustrated below. That does seem a bit peculiar. On the load line, do you have any large energy storage components like inductors or capacitors? If so, these could briefly hold the voltage up. Aside from that, when you remove power to this load, have you removed all power from your system, or have you only cut the power to INA198 sensor location of the system. If you cut the power locally, you may have some parasitic feed through from another supply rail. Yet another area to investigate is the device ground. Does your system have split ground planes or is there a large distance between the device ground and where you placed your ground probe? To determine if the device ground is floating up, I would probe directly at the device ground pin and the VIN+ pin.
