ACT4533A/B
Rev 0, 14-Aug-13
FUNCTIONAL BLOCK DIAGRAM FOR ACT4533A
FUNCTIONAL BLOCK DIAGRAM FOR ACT4533B
FUNCTIONAL DESCRIPTION
current level is measured by the Current Sense
Amplifier and added to the Oscillator ramp signal. If
the resulting summation is higher than the COMP
voltage, the output of the PWM Comparator goes
high. When this happens or when Oscillator clock
output goes low, the High-Side Power Switch turns
off.
CV/CC Loop Regulation
As seen in Functional Block Diagram, the
ACT4533A/B is a peak current mode pulse width
modulation (PWM) converter with CC and CV
control. The converter operates as follows:
A switching cycle starts when the rising edge of the
Oscillator clock output causes the High-Side Power
Switch to turn on and the Low-Side Power Switch to
turn off. With the SW side of the inductor now
connected to IN, the inductor current ramps up to
store energy in the magnetic field. The inductor
At this point, the SW side of the inductor swings to
a diode voltage below ground, causing the inductor
current to decrease and magnetic energy to be
transferred to output. This state continues until the
cycle starts again. The High-Side Power Switch is
Innovative PowerTM
- 5 -
www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
ACTIVE-SEMI [ ACTIVE-SEMI, INC ]
