Hi, Sirs,
We are using TI current sensor INA194AIDBVR. The architecture is as follows.
We would like to sense the current of DK_36V_OUT. The DK_36V_OUT is 36V +/-5%.
Even there is no load of DK_36V_OUT, INA194AIDBVR will output about 0~0.6V.
We checked and make sure the voltage difference of Vin+ and VIN-, it is 0V.
We test about 20PCS without load. The output value is different for all of them.
Dear Marx,
Thanks for choosing TI! Based on the description of your test, it sounds like you're running into issues with the lower Vsense condition on this device. The INA194-Q1 has special criteria that exists when Vsense < 20mV, found in section 7.4.2 of the datasheet. Based on the description of your test above, I can't determine where exactly your common mode falls, but I'm assuming that it is 36V based on nomenclature of the schematic, and this would mean that for this test you are operating inside case 3, which I've posted from the DS below. You can see here that in such a case, the device will behave atypcially, and an offset with a typical value of 300mV can appear at the pin, which sounds like the issue you are seeing. If Vcm is lower than supply, this voltage can be even worse than this
Was there a feature that drew you to the INA194-Q1 here? Given the need to drive the part to zero here, I would advise you to look at INA240-Q1 (INA240 if you do not need the automotive grade), or the new INA293-Q1, which operate much better at these low levels.
