Digital input circuit and method for high voltage sensors

摘要

A digital input circuit includes a series connection of a current limiter and a switch having a switch control input coupled between a signal input and ground, and a logic level shifter coupled to the signal input and having a switch control output coupled to the switch control input and a signal output, where a maximum amplitude at the signal input is greater than a maximum amplitude at the signal output. A digital input method includes coupling an input signal to ground with a current limiter by closing an electronic switch, providing an output signal responsive to the input signal, where a maximum amplitude of the input signal is greater than a maximum amplitude of the output signal, by latching the output signal while the input signal is above a threshold voltage and opening the electronic switch after the output signal is latched.

主权项

1. A digital input circuit comprising:
a series connection of a current limiter and a switch coupled between a signal input and ground, wherein the switch has a switch control input; a logic level shifter including a voltage comparator and a low pass filter, the logic level shifter being coupled to the signal input and having a switch control output coupled to the switch control input and a signal output, where a maximum amplitude at the signal input is greater than a maximum amplitude at the signal output; a clock coupled to the low pass filter; and an N-counter coupling the clock to the switch control input.