| 摘要 |
The switched mode power supply comprises an inductor, a switching transistor, a controller circuit coupled to the switching transistor, a rectifying means and a feedback regulation loop for providing a stabilised output voltage. It comprises further a protection circuit (PC) coupled to an output or input of a comparator of the controller circuit for providing an overvoltage protection in case of a failure of the regulation loop. The protection circuit comprises in particular an integrating circuit (IN1) and a comparating circuit (CO1). In a preferred embodiment, an output (E') of the protection circuit is coupled to a sense input of the controller circuit, for switching off the controller circuit immediately in case of a failure. In another aspect of the invention, the protection circuit comprises further a second comparator coupled to the first comparating circuit for the surveillance of the input voltage of the switched mode power supply, and for the detection of a short circuit of the inductor or the rectifying means. <IMAGE>
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