Abstract: In an over current protection circuit of a semiconductor switching device, a change in a main current of a semiconductor switching device with respect to a change in the detected voltage of the resistor for current detection connected to the current detection terminal of the semiconductor switching device becomes gentle in the vicinity of a location where the semiconductor switching device is turned off. With the provision of the current protection circuit, the variation in the cut-off level of the over current with respect to the variation in the detected voltage of the resistor for current detection connected to the current detection terminal of the semiconductor switching device is suppressed so that the semiconductor switching device can be protected from being breakdown due to the over current flow.

Abstract: A sensing and control circuit for power line shorts works especially well for sensor or actuator devices controlled through a microcontroller. A power control circuit is placed between a pin of a programmable microcontroller and a sensor or actuator device to act as a short detector and switch to control power to the device. A capacitor in the power control circuit is charged and sensed by a single pin of the microcontroller to regulate a transistor which switches power to the device.

Abstract: An AC to DC to AC converter has an input to receive input AC, a rectifier to rectify the input AC to DC, and an inverter to invert the DC to output AC. A load sensor senses load on the AC to DC to AC converter. A fan directs a cooling fluid to the AC to DC to AC converter. A fan control has an input coupled to the AC to DC to AC converter so as to receive DC therefrom, an input coupled to the load sensor, and an output coupled to the fan. The fan control controls the fan at a variable speed in response to load on the AC to DC to AC converter so as to vary the cooling fluid delivered by the fan to the AC to DC to AC converter.

Abstract: A protection circuit for a boost power converter provides input under-voltage protection and output over-voltage and over-current protection. The protection circuit includes a control power MOSFET connected in series between the ground of the boost power converter and the ground of the load. The arrangement of the circuit makes it easy to drive the gate of an N-channel power MOSFET and is ideal for current-limiting control, which utilizes the Rds-on of the MOSFET as a current sensing element. Neither a specific gate-driver nor a current sensing resistor is required, and thus high efficiency can be achieved. Furthermore, the slow slew-rate at the gate of the MOSFET provides a soft-start to the load. The protection circuit includes a temperature compensation circuitry to offset the variation of the Rds-on. A time delay circuit prevents the switching elements and protection elements from overload damage.