Patent ID: 7295414
Filing Date: 2007-11-13
Classification: H02M,H03K

Abstract:
1. A power output device, with a protection function for short circuit and overload, suitable for outputting an amplified voltage signal to a load, and the power output device comprising: a bridged output stage, comprising a transistor set, wherein the transistor set comprises two transistors connected in series between a power source and a ground, and the amplified voltage signal is outputted to the load from a connection node of the two transistors; a reference voltage generator, comprising at least a reference circuit, wherein the reference circuit comprises a reference transistor and a reference resistor connected in series, a size of the reference transistor is proportional to the transistors of the bridged output stage in a proportion factor, wherein the proportion ratio of the size of the reference transistor and the bridged output stage is the same as the proportion ratio of the resistance of the reference resistor and the load, such that a circuit configuration of the reference voltage generator is symmetrical to the bridged output stage, and a reference voltage range is accordingly generated; and a detecting unit, receiving a voltage difference across the two terminals of the turned-on transistors in the bridged output stage and comparing the received voltage difference with the reference voltage range generated by the reference voltage generator, wherein if an induced current of the load is over or the load is in short circuit, the voltage difference across the two terminals of the turned-on transistor in the bridged output stage exceeds the reference voltage range generated by the reference voltage generator, the detecting unit immediately turns off all transistors in the bridged output stage to stop outputting power to the load.