ACT4533
Rev 1, 25-Feb-13
Wide-Input Sensorless CC/CV Step-Down DC/DC Converter
FEATURES
• 40V Input Voltage Surge
• 32V Steady State Operation
• Up to 3A Output Current
• Constant Current Output with Input up to 32V
• Output Voltage up to 12V
• 125kHz Switching Frequency Eases EMI Design
• Good EMI Performance to Pass EN55022
Radiation Regulation without adding EMI
Components
• Patent Pending Active CC Sensorless Constant
Current Control
− Integrated Current Control Improves
Efficiency, Lowers Cost, and Reduces
Component Count
• Resistor Programmable
− Current Limit from 1.5A to 3A
− Patented Cable Compensation from 0 to 0.3Ω
• ±7.5% CC Accuracy
− Compensation of Input /Output Voltage Change
− Temperature Compensation
− Independent of inductance and Inductor DCR
• 2% Feedback Voltage Accuracy
• Up to 92% Efficiency
• Advanced Feature Set
− Integrated Soft Start
− Thermal Shutdown
− Secondary Cycle-by-Cycle Current Limit
− Protection Against Shorted ISET Pin
• SOP-8EP Package
APPLICATIONS
• Car Charger/ Adaptor
• Rechargeable Portable Devices
• General-Purpose CC/CV Supply
GENERAL DESCRIPTION
ACT4533 is a wide input voltage, high efficiency
Active CC step-down DC/DC converter that
operates in either CV (Constant Output Voltage)
mode or CC (Constant Output Current) mode.
ACT4533 provides up to 3A output current at
125kHz switching frequency.
Active CC is a patent-pending control scheme to
achieve highest accuracy sensorless constant
current control. Active CC eliminates the expensive,
high accuracy current sense resistor, making it ideal
for battery charging applications and adaptors with
accurate current limit. The ACT4533 achieves
higher efficiency than traditional constant current
switching regulators by eliminating its associated
power loss.
Protection features include cycle-by-cycle current
limit, thermal shutdown, and frequency foldback at
short circuit. The devices are available in a SOP-
8EP package and require very few external devices
for operation.
Innovative PowerTM
-1-
CC/CV Curve
6.0
VIN = 24V
5.0
4.0
VIN = 18V
3.0
VIN = 12V
2.0
1.0
0.0
0
400 800 1200 1600 2000 2400 2800
Output Current (mA)
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