Disclosed is a hair dryer having a reverse blowing dust-removal function, comprising a housing, a fan module, an air inlet, and an air outlet. The housing has a pass-through airflow channel between the air inlet and the air outlet. The fan module is disposed within the airflow channel of the housing. A circuit control board is disposed within the housing. A microcontroller and a power supply drive module are disposed on the circuit control board. The power supply drive module is connected to the fan module. The micro-controller is connected to the power supply drive module. A reverse rotation button and a forward rotation button that are connected to the micro-controller are disposed on the housing. The micro-controller controls, in response to a reverse rotation signal output by the reverse rotation button, the fan module to rotate in a reverse direction by means of the power supply drive module.

A protection circuit for protecting a load, such as a winch motor, from an overcurrent as well as from a circuit fault including welded primary switch contacts and a failure of its MOS/FET component. A power MOS/FET is used as a current mirror for sensing load current. A secondary switch is series connected to control the primary switch. A control circuit including a programmable data processor controls the MOS/FET and the secondary switch and senses the current through the MOS/FET's secondary source terminal and senses the voltage at its primary source terminal. The programmable data processor determines whether an overcurrent exists by comparing the sensed power circuit current to a stored overcurrent value and also senses whether the contacts of the primary switch are welded closed and whether the MOS/FET has been damaged. Additional conditions are sensed. Application of power to the load is prevented when such conditions are detected.

A short-circuit detection circuit is adapted to a full-bridge driver which includes the first and second high-side transistors respectively coupled from a supply voltage to the first and second output nodes and the first and second low-side transistors respectively coupled from the first and second output nodes to a ground. The short-circuit detection circuit includes the first and second voltage dividers respectively receiving voltages of the first and second output nodes to respectively generate the first and second voltages, the high-side and low-side selectors respectively selecting the first voltage and the second voltage to respectively generate a high-side voltage and a low-side voltage, a high-side comparator generating a high-side short-circuit signal when the high-side voltage is lower than a high-side reference voltage, and a low-side comparator generating a low-side short-circuit signal when the low-side voltage exceeds the low-side reference voltage.

A short-circuit detection circuit is adapted to a full-bridge driver which includes the first and second high-side transistors respectively coupled from a supply voltage to the first and second output nodes and the first and second low-side transistors respectively coupled from the first and second output nodes to a ground. The short-circuit detection circuit includes the first and second voltage dividers respectively receiving voltages of the first and second output nodes to respectively generate the first and second voltages, the high-side and low-side selectors respectively selecting the first voltage and the second voltage to respectively generate a high-side voltage and a low-side voltage, a high-side comparator generating a high-side short-circuit signal when the high-side voltage is lower than a high-side reference voltage, and a low-side comparator generating a low-side short-circuit signal when the low-side voltage exceeds the low-side reference voltage.