Dual-Threshold OVP Circuit for Staged Power Supply Shutdown

The patent divides the over-voltage protection function into two separate monitoring circuits: a first over-voltage monitoring circuit with a first threshold and a second over-voltage monitoring circuit with a second threshold. This segmentation allows each circuit to handle specific voltage ranges, improving overall protection reliability while maintaining manageable system complexity through modular design.

The patent implements dual threshold voltage levels (first threshold and second threshold) to create staged protection responses. When voltage exceeds the first threshold, the low voltage monitor circuit activates to reduce load voltage; when it exceeds the higher second threshold, the high voltage monitor circuit triggers complete power shutdown. This parameter differentiation enables graded protection that enhances reliability without requiring overly complex circuitry.

The protection system is segmented into two independent monitoring circuits, each with its own threshold and response mechanism. The first monitoring circuit handles moderate over-voltage conditions by controlling a transistor to reduce voltage, while the second monitoring circuit handles severe conditions by triggering complete shutdown. This segmentation protects against over-voltage damage while keeping each circuit segment relatively simple.

The patent introduces a transistor as an intermediary component between the first monitoring circuit and the load. The transistor acts as a voltage control element that the first monitoring circuit can adjust to reduce output voltage during moderate over-voltage conditions, providing a graceful intermediate response between normal operation and complete shutdown, thereby protecting loads without requiring direct complex circuit intervention.

The patent establishes two distinct voltage threshold parameters: a first threshold that triggers voltage reduction and a second threshold that triggers complete shutdown. This creates a staged safety mechanism where the system responds differently based on the severity of over-voltage conditions, providing broader safety margins while keeping control logic relatively simple through clear threshold-based decision making.

The first over-voltage monitoring circuit with its first threshold provides preliminary protection by activating before the second threshold is reached. When voltage exceeds the first threshold, the circuit preemptively reduces output voltage through transistor control, preventing the voltage from reaching dangerous levels that would trigger the second threshold and complete shutdown, thereby enhancing safety with a warning and intermediate protection stage.