| CPC G06F 13/10 (2013.01) [G06F 2213/40 (2013.01)] | 9 Claims |
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1. A sensor, comprising:
a switchable RC low-pass filter;
an evaluation unit;
a synchronization unit; and
a two-wire interface;
wherein the two-wire interface is configured:
to be connected to a control device to receive an electrical supply voltage, provided by the control device, for supplying the sensor with electrical energy,
to receive sync pulses superimposed on the supply voltage for synchronizing a data transmission from the control device, and
in a predefined time window, with respect to a sync point in time established by the synchronization unit, to transmit data to the control device, as a result of which data pulses resulting from the data transmission are superimposed on the supply voltage;
wherein the switchable RC low-pass filter is configured:
to generate a reference signal by low-pass filtering an input signal of the RC low-pass filter, wherein a waveform of the input signal corresponds with a waveform of the supply voltage that is superimposed,
to have a first time constant in a first mode of the RC low-pass filter, and
to have a second time constant in a second mode of the RC low-pass filter, wherein the second time constant is shorter than the first time constant;
wherein the evaluation unit is configured to stabilize the reference signal by:
switching the RC low-pass filter into the first mode at least when a sync pulse or data is superimposed on the supply voltage, and
switching the RC low-pass filter into the second mode at least in a period between two sync pulses in which no data are superimposed on the supply voltage; and
wherein the synchronization unit is configured:
to form a difference signal from the input signal and the reference signal, and
to determine a sync point in time whenever the difference signal exceeds a predefined threshold value.
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