Implementation Using A Multiplier

Implementation using a multiplier is an attractive option since this scheme can deliver nearly desired output voltage in spite of fluctuations in the source voltage. The scheme to be used is shown in Fig. 23.

The inputs to the multiplier are the source voltage or a part thereof and the output of the opamp in the feedback loop. Since the output of the multiplier should equal Vref representing the desired output voltage, the output of the opamp reflects the duty cycle. This signal can be compared with the output of a sawtooth generator and a pulse to turn on the switch can be obtained. If Vref can be modified to include the effects of drop in the switch, the output of the SMPS can equal the set value. The sixth applet simulates the SMPS controlled in this manner.

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