Open load diagnostics for loads that are PWM controlled
Abstract:
Methods and apparatuses for detecting an open load condition for a load. The load is coupled to a power source at a high side and to a ground at a low side through at least one switch, the load has a first end and a second end, a first voltage at the first end is kept constant. A switch is controlled by a PWM signal. After the switch is turned off by the PWM signal, the voltage associated with the second end of the load is measured. In one embodiment, a change of the second voltage during a predefined delay is compared with a predefined voltage threshold. In another embodiment, the time it takes for the change of the second voltage to reach a predefined voltage threshold is compared with a predefined time threshold.
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