Patent ID: 7840364

Claim:
A short-circuit detection circuit for detecting a short circuit of a signal line connected to a resolver in which an exciting signal is sent to an exciter coil and two detection signals of sine-phase and cosine-phase electromagnetically induced in two detection coils are output, the short-circuit detection circuit comprising: an exciting-line malfunction detection circuit for comparing potentials at both ends of the exciter coil to which the exciting signal is sent by a push-pull method; for detecting at least one of a short circuit to ground and a short circuit to a power supply of a signal line for the exciting signal based on a duty cycle of an exciting pulse signal that is a rectangular-wave indicating a result of the comparison of the potentials at both ends of the exciter coil; and for outputting an exciting-line malfunction detection signal indicating a result of the detection of the short circuit, wherein the exciting-line malfunction detection circuit comprises: a comparator for comparing the potentials at both ends of the exciter coil to generate the exciting pulse signal and for outputting the generated exciting pulse signal; a duty-cycle detection section for receiving the exciting pulse signal and for extracting and outputting a value corresponding to the duty cycle of the exciting pulse signal; and a threshold comparison section for receiving the value corresponding to the duty cycle of the exciting pulse signal, for comparing the value corresponding to the duty cycle of the exciting pulse signal with at least one of a value corresponding to a predetermined lower limit and a value corresponding to a predetermined upper limit to detect at least one of a short circuit to the ground and a short circuit to the power supply of the signal line for the exciting signal, and for outputting the exciting-line malfunction detection signal.