ACT4533B datasheet(5/18 Pages) ACTIVE-SEMI

5 / 18 page

ACT4533A/B

Rev 0, 14-Aug-13

Innovative Power

- 5 -

www.active-semi.com

FUNCTIONAL BLOCK DIAGRAM FOR ACT4533A

FUNCTIONAL DESCRIPTION

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

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.

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

FUNCTIONAL BLOCK DIAGRAM FOR ACT4533B

ACT4533B Datasheet(PDF) 5 Page - Active-Semi, Inc