| 摘要 |
A regulated power supply automatically accommodates either a positive or negative polarity connection of a power source and without regard as to whether the source is an DC or an AC source, and accommodating a wide range of input voltage sources. The power supply circuit includes a source voltage conditioning unit which includes an input fuse section, a surge protection circuit, a power switch, and a filter rectifier section, coupled in circuit between a set of external power source connection terminals and a set of output terminals from which a rectified and filtered intermediate voltage is derived. An open fuse detector alerts servicing personnel to an open condition of a user-replaceable input fuse. A DC-DC converter section includes a start up supply circuit and a primary drive winding of a power transformer connected to receive the intermediate rectified voltage from the filter rectifier of the input section. The primary drive winding is coupled to power switch MOSFETs, which drive the primary winding drive current under the control of a pulse width modulator (PWM). The outputs of plural secondary windings are rectified, filtered, and regulated. The rectified output of a selected secondary winding is monitored by way of current limiting and voltage feedback circuits to control the operation of the PWM.
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