This high-side, current sensing solution uses one comparator with a rail-to-rail input common mode range to create an over-current alert (OC-Alert) signal at the comparator output (COMP OUT) if the load current rises above 1 A. The OC-Alert signal in this implementation is active low. So when the 1-A threshold is exceeded, the comparator output goes low. Hysteresis is implemented such that OC-Alert will return to a logic high state when the load current reduces to 0.5 A (a 50% reduction). This circuit utlizes an open-drain output comparator in order to level shift the output high logic level for controlling a digital logic input pin. For applications needing to drive the gate of a MOSFET switch, a comparator with a push-pull output is preferred.
- Load current:
- Over current, Ioc = 1 A
- Recovery current, Irc = 0.5 A
- System supply typical Vs = 10 V
- Comparator output status:
- Over current: Vol < 0.4 V
- Normal operation: Voh = Vpu = 3.3 V