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PDF ACT4523A Data sheet ( Hoja de datos )
| Número de pieza | ACT4523A | |
| Descripción | Wide-Input Sensorless CC/CV Step-Down DC/DC Converter | |
| Fabricantes | Active-Semi | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ACT4523A (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
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ACT4523A
Rev 0, 25-Jul-13
Wide-Input Sensorless CC/CV Step-Down DC/DC Converter
FEATURES
• 40V Input Voltage Surge
• 36V Steady State Operation
• Up to 3.5A Output Current
• Output Voltage up to 12V
• 250kHz Switching Frequency
• 91% Efficiency (Vout = [email protected] at Vin = 12V)
• Patented ActiveCC Sensorless Constant Current
Control
− Integrated Current Control Improves
Efficiency, Lowers Cost, and Reduces
Component Count
• Resistor Programmable
− Current Limit from 1.5A to 4.0A
− Patented Cable Compensation from 0 to
0.25Ω
• ±6.5% CC Accuracy
− Compensation of Input /Output Voltage Change
− Temperature Compensation
− Independent of inductance and Inductor DCR
• 2% Feedback Voltage Accuracy
• 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
ACT4523A is a wide input voltage, high efficiency
ActiveCC step-down DC/DC converter that operates
in either CV (Constant Output Voltage) mode or CC
(Constant Output Current) mode. ACT4523A
provides up to 3.5A output current at 250kHz
switching frequency.
Active CC is a patented control scheme to achieve
highest accuracy with sensorless constant current
control. ActiveCC eliminates the expensive, high
accuracy current sense resistor, making it ideal for
battery charging applications and adaptors with
accurate current limit. The ACT4523A achieves
higher efficiency than traditional constant current
switching regulators by eliminating its associated
power loss on the sensing resistor. ACT4523A
provides OVP pin for output over voltage protection.
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 = 12V
5.0
4.0
VIN = 24V
3.0
2.0
1.0 VIN = 18V
0.0
1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
Output Current (A)
www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
1 page  
FUNCTIONAL BLOCK DIAGRAM
ACT4523A
Rev 0, 25-Jul-13
FUNCTIONAL DESCRIPTION
CV/CC Loop Regulation
As seen in Functional Block Diagram, the
ACT4523A 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.
regulating output voltage to regulating output
current, and the output voltage will drop with
increasing load.
The Oscillator normally switches at 250kHz.
However, if FB voltage is less than 0.6V, then the
switching frequency decreases until it reaches a
typical value of 36kHz at VFB = 0.15V.
Over Voltage Protection
The ACT4523A has an OVP pin. If the voltage at this
pin exceeds 0.8V, the IC shuts down high side switch.
Thermal Shutdown
The ACT4523A disables switching when its junction
temperature exceeds 155°C and resumes when the
temperature has dropped by 25°C.
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
driven by logic using HSB as the positive rail. This
pin is charged to VSW + 5V when the Low-Side
Power Switch turns on. The COMP voltage is the
integration of the error between FB input and the
internal 0.808V reference. If FB is lower than the
reference voltage, COMP tends to go higher to
increase current to the output. Output current will
increase until it reaches the CC limit set by the ISET
resistor. At this point, the device will transition from
Innovative PowerTM
- 5 - www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
5 Page 
TYPICAL PERFORMANCE CHARACTERISTICS
(Schematic as show in Figure 8, Ta = 25°C, unless otherwise specified)
ACT4523A
Rev 0, 25-Jul-13
Efficiency vs. Load Current
95
VIN =12V
90
85
80
VIN =18V VIN =24V
75
70
65
60
0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6
Load Current(A)
Switching Frequency vs. Input Voltage
290
280
270
260
250
240
230
220
210
10 15 20 25 30 35 40
Input Voltage (V)
Switching Frequency vs. Feedback Voltage
300
250
200
150
100
50
0
0 100 200 300 400 500 600 700 800 900
Feedback Voltage (mV)
2720
2700
2680
CC Current vs. Temperature
VOUT = 5V
VIN = 12V
IISET = 2.65A
2660
2640
2620
2600
2580
2560
-20
0
20 40 60 80 100 120 140
Temperature (°C)
2800
2750
CC Current vs. Input Voltage
VOUT = 5V
IISET = 2.65A
2700
2650
2600
2550
2500
10 15 20 25 30 35
Input Voltage (V)
40
Maximum Peak Current vs. Duty Cycle
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
20 30 40 50 60 70 80 90
Duty Cycle
Innovative PowerTM
- 11 -
www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet ACT4523A.PDF ] | |
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