Theory of operation

AN2389

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2.2

Buck converter implementation

If you keep SW2 always in OFF condition and drive SW1 (PWM1) with a PWM signal from

the microcontroller then the circuit works like a buck converter, except that you have an

Figure 3.

Buck converter implementation

If the duty cycle of the PWM signal driving SW1 (PWM1) is D1, the output voltage will be

given by:

PWM1

OFF

C

d1

P-

P+

L

d2

SW2