Siemens Aktiengesellschaft

Mario Seifert

Dieter Sass

Michael Frey

Stefan Haimerl

A method and a device for an open-load diagnosis of a switching stage includes the steps of turning off the switching transistor if, after a first delay time has elapsed since an appearance of a control signal, the output voltage is less than a first reference voltage, and if, after a second delay time has elapsed, the output voltage is less than a second reference voltage, then, with the switching transistor in the on state again, comparing the output current flowing through the switching transistor with a reference current, and if the output current is less than the reference current, effecting an open-load indication. The device includes a switchable buffer amplifier; a switching transistor, second and third transistors, a reference current source, first and second comparators, and a control circuit connected to the buffer amplifier, to the second and third transistors, and to the first and second comparators.

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Lengenfeld, Germany

Mario Seifert