Abstract: A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.

Abstract: A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.

Abstract: In a described example, a circuit includes a mode control circuit having an input and a mode control output. The mode control output is adapted to be coupled to a mode input of a DC-to-DC power converter. The mode control circuit is configured to provide a mode control signal at the mode control output. The mode control signal has a frequency and a duty cycle for causing the power converter to operate within an inaudible frequency range by transitioning the power converter between a power save mode and a pulse width modulation (PWM) mode. The mode control circuit is configured to control the duty cycle responsive to the input of the mode control circuit.

Abstract: In a described example, a circuit includes a mode control circuit having an input and a mode control output. The mode control output is adapted to be coupled to a mode input of a DC-to-DC power converter. The mode control circuit is configured to provide a mode control signal at the mode control output. The mode control signal has a frequency and a duty cycle for causing the power converter to operate within an inaudible frequency range by transitioning the power converter between a power save mode and a pulse width modulation (PWM) mode. The mode control circuit is configured to control the duty cycle responsive to the input of the mode control circuit.