Other Parts Discussed in Thread: TPS2051C
Tool/software:
I would like the check whether or not I am in danger of operating the INA180 out of specification in my application. I am unable to find any information in the datasheet which confirms this.
Briefly, as per the attached schematic, my application is using an INA180A3 to perform current-sensing of a load using the RDS(on) of a TPS2051C high-side load switch (~97mΩ) as the shunt resistance.
One thing I have observed is that when the load-switch is in the off state (when EN is low), I am measuring approximately 0.76V across the load output (regardless of whether load is connected). The TPS2051C features output-discharge when in the off state, which it does by switching the output to ground through a load resistance of approx. 470Ω. I believe current flowing through the INA180 caused by the relatively high differential input voltage across IN+/IN- (~5V) through this resistance accounts for the measured voltage.
The current appears to be flowing in through IN+ and out through IN- pins (i.e. not sourced from VS). I've calculated the current to be 0.76/470 = 1.6 mA. I've also experimented with a different load switch IC that, while largely functionally identical to the TPS2051C, features a stronger discharge resistance of 10Ω. In that case the output voltage measured is 0.02V, making 0.2/10 = 2.0 mA.
My question is: is this amount of current flow in/out of the input terminals allowable and within specification? I don't see anything in the datasheet in section 7.1 Absolute Maximum Ratings regarding maximum current for the input pins, only a note stating that "Input voltage at any pin can exceed the voltage shown if the current at that terminal is limited to 5 mA", which I presume refers to the capability of protection diodes on the inputs.
Functionally, everything with this circuit otherwise performs perfectly and this 0.7V output voltage is not a problem for my application, but I do not wish to stress the INA180 or cause any potential lifetime problems.