US 4,791,311 AGranted

Two-terminal multiplexable sensor

AssigneeSprague Electric Company

InventorRavi Vig

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Abstract

An integrated circuit field-to-electrical energy sensor is capable of being energized through two DC voltage supply terminals. Each of a plurality of such sensors, when connected in parallel so as to be energized from a single DC supply voltage source, is capable of recognizing by means of an address code comparator a unique pulse signal code superimposed on the DC supply voltage. Stimulated by that code which is unique to only that sensor, that sensor powers up the transducer, e.g. Hall element, and responds by drawing a particular current pattern from the common DC voltage source indicative of the presence (or absence) of a field, e.g. magnetic, that is ambient to that sensor. Electrically controlled energy to the transducer provided only when the unique code is present is supplied by the switchable of two regulated voltage outputs from a dual voltage regulator having a control input connected to the output of the address code comparator. The steady (unswitched) regulated output voltage supplies energy to the MOS logic including the address code comparator. The sensor quiescent current drawn from the DC voltage supply line is thereby caused to be a very low value which becomes increasingly advantageous as more and more sensors are operated in parallel on the same DC supply line.

Claims12

Dependent claims

A two-terminal multiplexable sensor comprising a silicon integrated circuit chip comprising:

(a) a power terminal and a ground reference terminal;
(b) a binary counter means connected to said power terminal for counting the number of voltage pulses of one polarity that are superimposed on a DC supply voltage applied to said power terminal;
(c) a fixed binary address code circuit means for providing a particular fixed-circuit binary-number address code by which said sensor may be distinguished electrically from other two-terminal multiplexable sensors;
(d) an address code comparator means connected between an output of said binary counter means and said fixed address code circuit means for providing at an output thereof a match signal only when the count of said counter means matches said address code;
(e) a switchable current source connected between said power terminal and said ground terminal and having a control input;
(f) an ambient-field-to-electrical-signal transducer, having an output connected to said control input of said current source, for switching on said current source when the ambient field strength exceeds a predetermined amount;
and
(g) a transducer control means connected between said output of said address code comparator means and said transducer
for turning on said transducer and switching on said current source for at least one particular portion of each period during which both the ambient field exceeds said amount and the count of said counter means matches said address code, so that the current-source current occuring during said one portion of each said period provides a signal through said power terminal indicating the presence of the ambient field that exceeds said amount, and
for turning off said transducer during all other periods during which the count of said counter means does not match said address code.

7 more elements

Dependencies are inferred from the claim text.