Integrated circuit pin for reference voltage and fault communication
A sensor integrated circuit includes a sensing circuit configured to generate the sensor output signal and a fault circuit to detect a fault and generate a fault signal indicative of the fault. A combined signal indicative of the fault signal when a fault is detected and indicative of a reference voltage associated with the sensor IC at other times is provided at a shared connection of the sensor IC. Embodiments include a current sensor IC and fault detectors configured to detect one or more faults.
1 . A sensor integrated circuit configured to generate a sensor output signal indicative of a sensed parameter, comprising:
a power connection configured to receive a supply voltage;
a ground connection;
a sensing circuit configured to generate the sensor output signal at a sensor output signal connection, wherein the sensing circuit has a reference voltage;
a fault circuit comprising a fault detector configured to detect a fault and generate a fault signal indicative of the fault; and
a combined connection at which a combined signal is provided, wherein the combined signal is indicative of the fault signal during times when the fault is detected and the reference voltage during times when the fault is not detected.
2 . The sensor integrated circuit of claim 1 further comprising a reference buffer coupled to receive the reference voltage.
3 . The sensor integrated circuit of claim 2 wherein the fault detector is further configured to generate a disable signal coupled to the reference buffer and configured to disable the reference buffer when a fault is detected.
4 . The sensor integrated circuit of claim 1 wherein the fault signal is a digital signal having a low level when a fault is detected.
5 . The sensor integrated circuit of claim 4 wherein the fault circuit further comprises a pull-down transistor controlled by the fault signal and configured to pull the combined signal to the low level when the fault is detected.
6 . The sensor integrated circuit of claim 4 wherein the fault is a first fault and the fault detector is further configured to detect a second fault, and wherein the fault circuit further comprises a push-pull circuit controlled by the fault signal and configured to pull the combined signal to the low level when the first fault is detected and pull the combined signal to a high level when the second fault is detected.
7 . The sensor integrated circuit of claim 1 wherein the fault is an overcurrent condition.
8 . The sensor integrated circuit of claim 7 wherein the sensed parameter is a current flow through a conductor and the overcurrent condition is an overcurrent condition of the current flow through the conductor.
9 . The sensor integrated circuit of claim 1 wherein the sensing circuit comprises a sensing element configured to generate a sensing element output signal and a processing path responsive to the sensing element output signal and configured to generate the sensor output signal.
10 . The sensor integrated circuit of claim 9 wherein the sensing element comprises a magnetic field sensing element and the sensed parameter is a magnetic field.
11 . The sensor integrated circuit of claim 9 wherein the processing path comprises a front-end amplifier coupled to receive the sensing element output signal and configured to generate an amplifier output signal.
12 . The sensor integrated circuit of claim 1 wherein the reference voltage is at a voltage level of approximately one-half the supply voltage.
13 . The sensor integrated circuit of claim 1 wherein the combined connection is configured for coupling to an external buffer or an external inverter to generate a level-shifted combined signal.
14 . The sensor integrated circuit of claim 1 wherein the sensor integrated circuit has exactly four pins.
15 . A method comprising:
generating a sensor output signal indicative of a sensed parameter at a sensor output signal connection with a sensing circuit having a reference voltage;
generating a fault signal indicative of a fault being detected; and
generating a combined signal indicative of the reference voltage and the fault signal during times when the fault is detected and the reference voltage during times when the fault is not detected.
16 . The method of claim 15 further comprising buffering the reference voltage with a reference buffer.
17 . The method of claim 16 further comprising disabling the reference buffer when the fault is detected.
18 . The method of claim 15 wherein generating the fault signal comprises generating a low level signal when the fault is detected.
19 . The method of claim 18 wherein generating the combined signal comprises pulling the combined signal to the low level when a fault is detected.
20 . The method of claim 18 wherein generating the fault signal comprises generating the fault signal indicative of a first fault or a second fault and wherein generating the combined signal comprises pulling the combined signal to the low level when the first fault is detected and pulling the combined signal to a high level when the second fault is detected.
21 . The method of claim 15 wherein the fault comprises an overcurrent condition.
22 . The method of claim 15 wherein the sensed parameter is a magnetic field associated with a current flow through a conductor and wherein generating the sensor output signal comprises sensing the magnetic field with a magnetic field sensing element.