Improved Switched Mode Power Supply Regulation by Eliminating Turn-Off Spikes
Original Publication Date: 1988-Sep-01
Included in the Prior Art Database: 2005-Feb-15
In a switch mode power supply (SMPS), a transistor is used to switch out the power-on disturbance at the leading edge of the sense winding waveform. The sense voltage assumes the desired DC level and is not influenced by this disturbance. This technique substantially improves the output dynamic cross-regulation. This circuit is applicable to any flyback SMPS which uses a sense winding in the control loop. It is particularly useful in a power supply where good cross-regulation is required, for example, in a display monitor power supply also providing external power to diskette drives. In a flyback SMPS, the lowest cost method of closing the feedback loop is often to use a dummy sense winding on the primary side of the transformer. In this configuration (Fig.