Microcontroller 80 can interpret signal 250 to determine that a fault is present before time t1 and after time t2, so that the differential measurement waveform 240 is not to be interpreted as an indication of the conductor current during these times. Whereas between times t1 and t2, microcontroller 80 can interpret differential measurement waveform 240 to be an accurate indication of the conductor current.

Referring also to FIG. 3, a sensor system 300 includes an alternative sensor IC 320 having a shared fault signal and reference voltage connection 324c at which a combined VREF/FAULT signal 350 is provided.

Sensor IC 320 is configured to generate a sensor output signal 334 that may be the same as or similar to output signal 34 of FIG. 1 and thus, that is indicative of a sensed parameter associated with a target 314. Example target 314 is an integrated current carrying conductor, as shown.

Sensor IC 320 differs from sensor IC 20 in fault circuit 340. In particular, fault circuit 340 is configured to provide a fault signal that can distinguish between more than one fault. To this end, fault circuit 340 can include a push-pull circuit that is configured to pull the combined signal 350 to a low level when a first fault is detected and pull the combined signal to a high level when a second fault is detected, as will be described.

In other respects, sensor IC 320 can be the same as or similar to sensor IC 20. To this end, sensor IC 320 includes a power connection 324a configured to receive a supply voltage VCC, a ground connection 324d, and a sensing circuit 330. Sensing circuit 330 has a reference voltage VREF represented by block 354 and is configured to generate the sensor output signal 334 at a sensor output connection VOUT 324b.

Sensing circuit 330 can include one or more sensing elements 336 coupled to processing circuitry 338. Sensing elements 336 can be Hall effect elements arranged to make a differential magnetic field measurement. A bias circuit 328 can provide bias current to the elements 336.

Processing circuitry 338 may include a front-end amplifier and/or a filter. Sensor output signal 334 can be an analog signal having a voltage level indicative of the current through conductor 314.

Reference voltage block 354 can generate a reference voltage 356 indicative of the quiescent voltage output for the sensor output VOUT. Reference voltage 356 can be buffered by a buffer 358. Generally, the reference voltage 356 is one-half of the VCC supply voltage level.

Fault circuit 340 can be configured to detect an overcurrent condition of the current conductor 314. To this end, circuit 340 includes a window comparator arrangement including comparators 346, 348, each of which compares the output signal 334 to an overcurrent reference 342. When the output signal 334 is greater than the overcurrent reference 342, the output of comparator 348 can transition to a high level to turn on NMOS transistor 364 in order to thereby pull up the combined signal 350 to a low level or ground; whereas, when the output signal 334 is less than the overcurrent reference 342, the output of comparator 346 can transition to a low level to turn on PMOS transistor 362 in order to thereby pull the combined signal 350 to a high level. In this way, in the presence of a first fault (e.g., a positive overcurrent fault), the combined signal 350 is pulled to ground and in the presence of a second fault (e.g., a negative overcurrent fault), the combined signal 350 is pulled to VCC.

Thus, the fault circuit 340 is bidirectional in that it detects a current level through conductor 314 that is greater than a predetermined positive current or less than a predetermined negative current; however, unlike the bidirectional overcurrent detection of FIG. 1, in FIG. 3, the resulting fault detection is different depending on which type of fault is detected.

In “normal” operation, when there is no fault detected by fault circuit 340, the combined signal 350 at shared output 324c provides the reference voltage VREF. In other words, when the sensor IC 320 is operating normally, the VREF/FAULT pin 324c will output the sensor reference voltage which is typically a voltage of approximately VCC/2.

In the case of a fault condition such as an overcurrent or short circuit condition, the reference buffer 358 is disabled and the VREF/FAULT pin 324c is pulled up through transistor 362 or down through transistor 364, depending on the particular fault condition, as described above. For example, when a fault occurs and is detected, a disable signal 344 can be provided to buffer 358 in order to disable the buffer. Disable signal 344 can be generated in various ways as a logical OR of the outputs of comparators 346, 348 so that when either comparator trips to thereby indicate the occurrence of a fault condition, the disable signal 344 changes state to disable the buffer 358.

It will be appreciated by those of ordinary skill in the art that disabling the reference buffer 358 can prevent unnecessary power dissipation associated with the buffer sinking current to ground and/or preventing damage to the buffer depending on the buffer design.

System 300 can further include an external microcontroller 380 with which sensor IC 320 communicates. Microcontroller 380 can be the same as or similar to microcontroller 80 except that a GPIO input need not be provided. This is because the configuration of fault circuit 340 effectively translates the combined signal 350 out of the normal operating range when a fault is detected and doing so facilitates interpretation of a fault condition by the microcontroller 380 as will become apparent from consideration of example waveforms in connection with FIG. 4.

Microcontroller 380 is configured to receive sensor output signal 334 at an ADCIN1 connection 384b and to receive the combined VREF/FAULT signal 350 at an ADCIN2 connection 384c. An ADC 386 coupled to the ADCIN1 connection 384b can convert the received sensor output signal 334 into a digital signal for further processing and/or action. An ADC 388 coupled to the ADCIN2 connection 384c can convert the received combined VREF/FAULT signal 350 into a digital signal for further processing and/or action.

When the combined signal 350 provides the VREF voltage (i.e., in the absence of a fault detection), microcontroller 380 can process the sensor output signal 334 and the VREF voltage in a differential manner in order to remove errors attributable to reference voltage shifts and/or noise.

When the combined signal 350 indicates that a fault has been detected, microcontroller