Patent ID: 6456156
Filing Date: 2002-09-24
Classification: F02D,F02P,Y02T

Abstract:
A method for an open-load diagnosis of a switching stage, which comprises:providing a switching stage having a load connected in series with at least one switching transistor; defining a predetermined first delay time period; starting a count of the first delay time period upon receipt of a control signal; waiting for the first delay time period to elapse, subsequently comparing an output voltage across the switching transistor with a predetermined first reference voltage, and: terminating the open-load diagnosis and maintaining a driving of the switching stage until an end of the control signal where the output voltage is greater than the predetermined first reference voltage; and turning off the switching transistor and starting a count for a predetermined second delay time period where the output voltage is less than the predetermined first reference voltage; during the course of the second delay time period, comparing the output voltage with a predetermined second reference voltage, and, where the output voltage is greater than the predetermined second reference voltage: terminating the open-load diagnosis; turning on the switching transistor again; and maintaining the driving of the switching stage until the end of the control signal; where the output voltage is less than the predetermined second reference voltage after the second delay time period has elapsed, comparing one of: an output current flowing through the switching transistor; and a voltage proportional to the output current with at least one of a predetermined reference current and a voltage proportional to the predetermined reference current, and terminating the open-load diagnosis and maintaining the driving of the switching stage until the end of the control signal where the output current is greater than the predetermined reference current; and effecting an open-load indication where the output current is less than the predetermined reference current; and repeating the open-load diagnosis from an end of the first delay time period until the end of the control signal after a predetermined waiting time period has elapsed.