Patent ID: 7986537

Claim:
An overcurrent-protected, switching-mode power supply for DC-to-DC conversion, comprising: (a) DC input means for inputting a DC voltage; (b) DC output means for outputting a DC voltage; (c) inductance means connected to the DC input means; (d) an active switch connected to the DC input means via the inductance means for switching the DC input voltage on and off; (e) a rectifying and smoothing circuit connected between the inductance means and the DC output means for providing the DC output voltage for application to the DC output means; (f) an output voltage detector circuit connected to the rectifying and smoothing circuit for detecting the DC output voltage; (g) switch control signal generator means connected between the output voltage detector circuit and the active switch for turning the latter on and off to keep the DC output voltage constant; (h) current detect means for providing an uncorrected current detect signal indicative of a current flowing through the active switch; (i) current detect signal correction means connected to the switch control signal generator means and the current detect means for providing a corrected current detect signal by generating a correction signal which grows with time during each conducting period of the active switch and by subtracting the correction signal from the uncorrected current detect signal; (j) an overcurrent threshold source for providing a signal indicative of an overcurrent threshold of the current flowing through the active switch; and (k) a comparator having a first input connected to the current detect signal correction means, a second input connected to the overcurrent threshold source, and an output connected to the switch control signal generator means, for causing the switch control signal generator means to turn off the active switch when the corrected current detect signal rises to the overcurrent threshold.