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PDF ACT4514 Data sheet ( Hoja de datos )
| Número de pieza | ACT4514 | |
| Descripción | Wide-Input Sensorless CC/CV Step-Down DC/DC Converter | |
| Fabricantes | Active-Semi | |
| Logotipo |  |
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Active-Semi
ACT4514
Rev 1, 21-Jul-11
Wide-Input Sensorless CC/CV Step-Down DC/DC Converter
FEATURES
• Up to 40V Input Voltage
• Up to 1.5A Constant Output Current
• Output Voltage up to 12V
• Patent Pending ActiveCC Constant Current
Control
− Integrated Current Control Improves
Efficiency, Lowers Cost, and Reduces
Component Count
• Resistor Programmable Outputs
− Current Limit from 400mA to 1500mA
− Patented cable compensation from DC Cable
Compensation from 0Ω to 0.5Ω
• 2% Feedback Voltage Accuracy
• Up to 93% Efficiency
• 210kHz Switching Frequency Eases EMI Design
• Advanced Feature Set
− Integrated Soft Start
− Thermal Shutdown
− Secondary Cycle-by-Cycle Current Limit
− Protection Against Shorted ISET Pin
• SOP-8 Package
APPLICATIONS
• Car Charger
• Rechargeable Portable Devices
• General-Purpose CC/CV Power Supply
GENERAL DESCRIPTION
ACT4514 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. ACT4514
provides up to 1.5A output current at 210kHz
switching frequency.
ActiveCC is a patent-pending control scheme to
achieve highest accuracy sensorless constant
current control. ActiveCC eliminates the expensive,
high accuracy current sense resistor, making it ideal
for battery charging applications and high-
brightness LED drive for architectural lighting. The
ACT4514 achieves higher efficiency than traditional
constant current switching regulators by eliminating
the sense resistor and 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-8
package and require very few external devices for
operation.
Innovative PowerTM
CC/CV Curve vs. Load Current
6.0
V0UT = 5V
5.0
4.0
3.0 VIN = 12V
VIN = 24V
2.0
1.0
0.0
0
150 300 450 600 750 900
IOUT Current (mA)
- 1 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.
1 page  
Active-Semi
ACT4514
Rev 1, 21-Jul-11
FUNCTIONAL BLOCK DIAGRAM
AVIN
IN
BANDGAP,
REGULATOR,
EN &
OSCILLATOR
SHUTDOWN
CONTROL
VREF = 0.808V
VREF = 0.808V
FB
+
-
CC
CONTROL
COMP
ISET
PVIN
EMI
CONTROL
PWM
CONTROLLER
HSB
SW
FUNCTIONAL DESCRIPTION
CV/CC Loop Regulation
As seen in Functional Block Diagram, the ACT4514
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
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
regulating output voltage to regulating output
current, and the output voltage will drop with
increasing load.
The Oscillator normally switches at 200kHz.
However, if FB voltage is less than 0.6V, then the
switching frequency decreases until it reaches a
typical value of 30kHz at VFB = 0.15V.
Enable Pin
The ACT4514 has an enable input EN for turning
the IC on or off. The EN pin contains a precision
0.8V comparator with 75mV hysteresis and a 4µA
pull-up current source. The comparator can be used
with a resistor divider from VIN to program a startup
voltage higher than the normal UVLO value. It can
be used with a resistor divider from VOUT to disable
charging of a deeply discharged battery, or it can be
used with a resistor divider containing a thermistor
to provide a temperature-dependent shutoff
protection for over temperature battery. The
thermistor should be thermally coupled to the
battery pack for this usage.
If left floating, the EN pin will be pulled up to roughly
5V by the internal 4µA current source. It can be
driven from standard logic signals greater than
0.8V, or driven with open-drain logic to provide
digital on/off control.
Thermal Shutdown
The ACT4514 disables switching when its junction
temperature exceeds 155°C and resumes when the
temperature has dropped by 20°C.
Innovative PowerTM
- 5 - www.active-semi.com
Copyright © 2011 Active-Semi, Inc.
5 Page 
Active-Semi
Figure 9:
Typical Application Circuit for 5V/0.75A Car Charger
ACT4514
Rev 1, 21-Jul-11
Table 3:
BOM List for 5V/0.75A Car Charger
ITEM REFERENCE
DESCRIPTION
1 U1 IC, ACT4514SH, SOP-8
2 C1 Capacitor, Electrolytic, 47µF/50V, 6.3х7mm
3 C2 Capacitor, Ceramic, 2.2µF/50V, 1206, SMD
4 C3 Capacitor, Ceramic, 1.5nF/6.3V, 0603, SMD
5 C4 Capacitor, Ceramic, 10nF/50V, 0603, SMD
6 C5 Capacitor, Electrolytic, 100µF/10V, 6.3х7mm
7 C6 Capacitor, Ceramic, 1µF/10V, 0603, SMD
8 C7 (Optional) Capacitor, Ceramic, 220pF/6.3V, 0603
9 L1 82µH, 1A, 20%, SMD 1058-MGDN6-00013
10 D1 Diode, Schottky, 40V/2A, SB240, DO-15
11 D2 Diode, 75V/150mA, LL4148
12 R1 Chip Resistor, 33kΩ, 0603, 1%
13 R2 Chip Resistor, 52kΩ, 0603, 1%
14 R3 Chip Resistor, 12kΩ, 0603, 5%
15 R4 Chip Resistor, 10kΩ, 0603, 1%
MANUFACTURER
Active-Semi
Murata, TDK
Murata, TDK
Murata, TDK
Murata, TDK
Murata, TDK
Murata, TDK
Murata, TDK
Tyco Electronics
Diodes
Good-ARK
Murata, TDK
Murata, TDK
Murata, TDK
Murata, TDK
QTY
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Innovative PowerTM
- 11 -
www.active-semi.com
Copyright © 2011 Active-Semi, Inc.
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ACT4514.PDF ] | |
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