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ACT4513 Schematic ( PDF Datasheet ) - Active-Semi

Teilenummer ACT4513
Beschreibung Wide-Input Sensorless CC/CV Step-Down DC/DC Converter
Hersteller Active-Semi
Logo Active-Semi Logo 




Gesamt 16 Seiten
ACT4513 Datasheet, Funktion
ACT4513
Rev 7, 14-Nov-12
Wide-Input Sensorless CC/CV Step-Down DC/DC Converter
FEATURES
Up to 40V Input Voltage
Up to 2A output current
Output Voltage up to 12V
Patent Pending Active CC Sensorless Constant
Current Control
Integrated Current Control Improves
Efficiency, Lowers Cost, and Reduces
Component Count
Resistor Programmable
Current Limit from 750mA to 2A
Patented Cable Compensation from 0to
0.5
±7.5% CC Accuracy
Compensation of Input /Output Voltage Change
Temperature Compensation
Independent of inductance and Inductor DCR
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-8EP Package
APPLICATIONS
Car Charger/ Adaptor
Rechargeable Portable Devices
General-Purpose CC/CV Supply
GENERAL DESCRIPTION
ACT4513 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.
ACT4513 provides up to 2A output current at
210kHz 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 ACT4513 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 = 12V
3.0
2.0
1.0
0.0
0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7
Output Current (A)
www.active-semi.com
Copyright © 2012 Active-Semi, Inc.






ACT4513 Datasheet, Funktion
ACT4513
Rev 7, 14-Nov-12
APPLICATIONS INFORMATION
Output Voltage Setting
Figure 1:
Output Voltage Setting
CC Current Line Compensation
When operating at constant current mode, the
current limit increase slightly with input voltage. For
wide input voltage applications, a resistor RC is
added to compensate line change and keep output
high CC accuracy, as shown in Figure 3.
Figure 3:
Iutput Line Compensation
Figure 1 shows the connections for setting the
output voltage. Select the proper ratio of the two
feedback resistors RFB1 and RFB2 based on the
output voltage. Typically, use RFB2 10kand
determine RFB1 from the following equation:
R FB1
=
RFB 2
⎜⎛
VOUT
0.808V
1 ⎟⎞
(1)
CC Current Setting
ACT4513 constant current value is set by a resistor
connected between the ISET pin and GND. The CC
output current is linearly proportional to the current
flowing out of the ISET pin. The voltage at ISET is
roughly 1V and the current gain from ISET to output
is roughly 25000 (25mA/1µA). To determine the
proper resistor for a desired current, please refer to
Figure 2 below.
Figure 2:
Curve for Programming Output CC Current
Output Current vs. RISET
2400
2000
1600
1200
800
400
0
0 10 20 30 40 50 60 70 80 90
RISET (k)
VIN
Rc
RISET
IN
ACT4513
ISET
Inductor Selection
The inductor maintains a continuous current to the
output load. This inductor current has a ripple that is
dependent on the inductance value:
Higher inductance reduces the peak-to-peak ripple
current. The trade off for high inductance value is
the increase in inductor core size and series
resistance, and the reduction in current handling
capability. In general, select an inductance value L
based on ripple current requirement:
( )L
=
VOUT
×
VIN
V_
OUT
V f I KIN SW LOADMAX RIPPLE
(2)
where VIN is the input voltage, VOUT is the output
voltage, fSW is the switching frequency, ILOADMAX is
the maximum load current, and KRIPPLE is the ripple
factor. Typically, choose KRIPPLE = 30% to
correspond to the peak-to-peak ripple current being
30% of the maximum load current.
With a selected inductor value the peak-to-peak
inductor current is estimated as:
( )ILPK _PK
=
VOUT
×
VIN
V_
OUT
L ×VIN × fSW
(3)
The peak inductor current is estimated as:
ILPK
=
ILOADMAX
+
1
2
I
LPK
_PK
(4)
Innovative PowerTM
- 6 - www.active-semi.com
Copyright © 2012 Active-Semi, Inc.

6 Page









ACT4513 pdf, datenblatt
ACT4513
Rev 7, 14-Nov-12
TYPICAL PERFORMANCE CHARACTERISTICS CONT’D
(L = 33µH, CIN = 10µF, COUT = 47µF, Ta = 25, RCOMP = 8.2k, CCOMP1 = 2.2nF, CCOMP2 = NC)
Shutdown Current vs. Input Voltage
130
120
110
100
90
80
70
10
15 20 25 30 35
Input Voltage (V)
40
Reverse Leakage Current (VIN Floating)
160
120
80
40
0
01 2 3 4 5
VOUT (V)
Start up into CC mode
VOUT = 5V
RLORD = 1.5
IISET = 2A
VIN = 24V
CH1
Standby Current vs. Input Voltage
3.6
3.2
2.8
2.4
2
1.6
1.2
0.8
0.4
0
0 4 8 12 16 20 24 28 32 36 40
Input Voltage (V)
Start up into CC mode
VOUT = 5V
RLORD = 1.5
IISET = 2A
VIN = 12V
CH1
CH2
CH1: VOUT, 2V/div
CH2: IOUT, 1A/div
TIME: 200µs/div
SW vs. Output Voltage Ripples
VIN = 12V
VOUT = 5V
IOUT = 2A
CH1
CH2
CH1: VOUT, 2V/div
CH2: IOUT, 1A/div
TIME: 200µs/div
Innovative PowerTM
- 12 -
CH2
CH1: VOUT Ripple, 20mV/div
CH2: SW, 5V/div
TIME: 2µs/div
www.active-semi.com
Copyright © 2012 Active-Semi, Inc.

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