Patent ID: 6665197
Filing Date: 2003-12-16
Classification: H02M

Abstract:
A circuit configuration for producing a switching signal for a current-controlled switch-mode power supply having transformer with at least one primary winding and with at least one secondary winding and an input DC voltage, comprising:a controlled power switch to be connected to the input DC voltage in series with the at least one primary winding; a drive circuit connected to said power switch, said drive circuit switching said power switch on and off clocked in time with a signal having a clock frequency; a current measurement device connected to said power switch, said current measurement device measuring a current level through said power switch and producing a measurement signal being a measure of said measured current level; a reference signal source producing a reference signal, said reference signal being a constant reference signal independent of time; a comparator circuit connected to said drive circuit, to said current measurement device, and to said reference signal source, said comparator circuit comparing said measurement signal with said reference signal and signaling said drive circuit to switch off said power switch when said measurement signal is greater than said reference signal; and said reference signal source having an associated compensation signal source producing a compensation signal varying with time, said reference signal being obtained from a sum of said constant reference signal and said compensation signal, said reference signal at a time at which said power switch is switched on having a value less than at a time of said signal at which said power switch is switched off.