Other Parts Discussed in Thread: TPS37, TPS38,
We have a relay that we want to energize when our input voltage goes above a certain voltage, 20V probably. that same input voltage is also the power for all circuitry of the design. The input voltage goes to a few different voltages on start up to work on detecting PoE loads, and that voltage is always below 18V. The voltage detection relies on measuring a resistance value at those various voltages.
Any impedance from the relay coil or other "downstream"parts must not interfere with that measurement. So my idea was to have a voltage supervisor keep an output set low/high while the input is below 20V, and then once the input goes above 20V to a max of ~50V, then the supervisor flips that signal. I would want to drive the gate of a FET with the idea that the FET is making sure the relay coil (and potentially other loads) are blocked and look like very high impedance when the input voltage is below 20V.
I want to make sure that of what happens to the operation of the TPS3760 (or the TPS37 or TPS38 as other choices) when the Supply Voltage and the Sense Voltage are identical and vary over time.
Will this work as is, or is there something I should do to the sense line input?
Perhaps using a fixed-reference version of the chip where it is a C4 option (or some other lower voltage) and I change my 7k to a divider to sneak off a lower voltage that would track the input voltage?
Can you recommend a particular version with a proper voltage reference?
So something like this, with maybe not needing R1 depending on TPSxx's abilities.