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LT1789-10 Maximum Gain + Input Limitations

Category: Datasheet/Specs
Product Number: LT1789-10

I'm using an LT1789-10 at the core of a milliohm meter project. I'm only learning about electronics and this is my way of getting my head around things.

I've modeled the whole circuit in LTspice and it's all simulating well. I have a few questions for the EngineerZone and i'll get through all of these progressively.

My first question here is about the gain on the LT1789-10. I've tried simulating a theoretical gain of 10000 which is out of spec, or at least is not documented.

The circuit is simulating well at this gain, but I wonder what pitfalls are ahead if I implement this in reality.

My second question is - Is the implementation of the zener/resistor across the input of the LT1879 the best way to limit the voltage from getting too close to the LT1789 rails when there is no DUT in place? I don't even know for sure if this is a problem for the LT1789 as the datasheet isn't completely clear to me. The zener/resistor certainly stops the current source from generating the 100mA current when there is no DUT in place.

Milliohm Meter7.5.asc

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