Current-limiting circuit and apparatus

摘要

Embodiments of the present invention relate to the field of electronic technologies, and provide a current-limiting circuit and apparatus to reduce costs of the current-limiting circuit and an occupied PCB board area. The circuit comprises a detecting resistor, a current-limiting resistor, a precise current unit, a power metal oxide MOS transistor, an operational amplifier OP and an input voltage end.

主权项

1. A current-limiting circuit, comprising a detecting resistor, a current-limiting resistor, a precise current unit, a power metal oxide semiconductor MOS transistor, an operational amplifier OP and an input voltage end, wherein the OP comprises a non-inverting input end, an inverting input end and an output end;
the input voltage end is configured to receive an input voltage; one end of the detecting resistor is connected to the input voltage end, and the other end of the detecting resistor is connected to the non-inverting input end of the OP, and the detecting resistor is provided with at least one resistance value, and a resistance value of the detecting resistor may be adjusted to one resistance value among the at least one resistance value; one end of the current-limiting resistor is connected to the input voltage end, and the other end of the current-limiting resistor is connected to the inverting input end of the OP; the precise current unit is connected to the other end of the detecting resistor and is configured to adjust a proportional error between the current-limiting resistor and the detecting resistor by outputting a precise reference current; and the power MOS transistor comprises a gate electrode, a source electrode and a drain electrode, wherein the gate electrode is connected to the output end of the OP, the source electrode is connected to the other end of the current-limiting resistor, and the drain electrode outputs a current-limiting current corresponding to one resistance value.