Current Sense Amplifier INA180 Negative Supply Measurement?

[Jay_Diddy_B]

Hi group,

Here is Figure 29 from the Linear Tech application note AN105.




The circuit is the same topology that I proposed earlier in this thread.

The circuit uses a zero-drift, chopper-stabilized op-amp in the first position. The offset voltage of this op-amp get multiplied by the gain of the circuit, in this case x100.

The circuit includes some capacitors to reduce the bandwidth.

Protection, if needed can be added, the same way as described by Ian.M and illustrated here:



Jay_Diddy_B

[LoveLaika]

If the Zener acts in the way that I think it does, isn't it safe, barring unusual conditions?  Since its referenced to the low negative voltage, the Zener ensures a 5 volt difference between its rails so that would allow it to tolerate very low negative voltages?

[ledtester]

The Zener and the corresponding resistor (the 39K in the  LT app note and R5 in Jay_Diddy_B's circuit) form a classic zener voltage regulator.

The main design concern is to pick the resistor so that there is enough current for regulation and the device receiving the regulated power while staying within the power limits of the zener diode.