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Power Management Integrated Circuits
capacitors, produces the regulated DC output. The regulator IC compares a portion of the
rectifi
ed DC output with a voltage reference ( V
REF
) and varies the PWM duty cycle to
maintain a constant DC output voltage. If the output voltage wants to increase, the PWM
lowers its duty cycle to reduce the regulated output, keeping it at its proper voltage level.
Conversely, if the output voltage tends to go down, the feedback causes the PWM duty
cycle to increase and maintain the proper output.
V
IN
V
OUT
R
1
R
2
Error
amplifier
Inductor
PWM
Voltage
ref
Schottky
diode
oscillator
Figure 6.9 : Simplifi ed ...