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PDF AAT3140 Data sheet ( Hoja de datos )
| Número de pieza | AAT3140 | |
| Descripción | High Efficiency 1X/1.5X/2X Charge Pump | |
| Fabricantes | AAT | |
| Logotipo |  |
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AAT3140
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
General Description
Features
ChargePump™
The AAT3140 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-mode
load switch (1X), fractional (1.5X), and doubling (2X)
conversion to maximize efficiency for white LED appli-
cations. The device produces current levels up to
30mA on each of its four current source outputs to
drive various arrangements of LEDs from a 2.7V to
5.5V input. Outputs may be operated individually or in
parallel for driving higher-current LEDs. A low external
parts count (two 1µF flying capacitors and two small
1µF capacitors at VIN and CP) make the AAT3140 ide-
ally suited for small battery-powered applications.
The AAT3140 is equipped with AnalogicTech’s unique
AutoBias™ technology which allows individual LEDs
to be powered either by charge pump or battery input,
determined internally and automatically to maximize
the power efficiency even with a large difference in
LED forward voltage.
• VIN Range: 2.7V to 5.5V
• Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and VF Coverage
• Drives Low-VF and High-VF Type LEDs
• Up to Four 30mA Outputs
• 32-Position Logarithmic Scale with Digital
Control
• Low Noise Constant Frequency Operation
• 1MHz Switching Frequency
• AutoBias Technology
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• IQ < 1µA in Shutdown
• 12-Pin TSOPJW Package
AnalogicTech's Simple Serial Control™ (S2Cwire™)
digital input is used to enable, disable, and set the
Applications
LED drive current with a 32-level logarithmic scalewww.DataSheet4U.com
LED brightness control. The AAT3140 has a thermal
management system to protect the device in the event
of a short-circuit condition at an output pin. Built-in soft-
start circuitry prevents excessive inrush current during
•
•
•
•
Color (RGB) Lighting
Programmable Current Sources
White LED Backlighting
White Photo Flash for Digital Still Cameras
start-up. A high charge pump switching frequency
enables the use of very small external capacitors. In
shutdown mode, the device disconnects the load from
VIN and reduces quiescent current to less than 1µA.
The AAT3140 is available in the very small, Pb-free
12-pin TSOPJW package.
Typical Application
VBATTERY
CIN CCP
1μF 1μF
EN/SET
VIN C1+
CP C1-
C2+
AAT3140
C2-
EN/SET
D1
D2
D3
D4
GND
C1
1μF
C2
1μF
D4 D3 D2 D1
3140.2007.03.1.3
1
1 page  
AAT3140
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Typical Characteristics
VIN = 3.5V, CIN = CCP = C1 = C2 = 1µF, TA = 25°C, unless otherwise noted.
Efficiency vs. Input Voltage
(Code 26)
Efficiency vs. Input Voltage
(D1 = 3.5V, D2 = 3.3V, D3 = 3.2V, D4 = 3.0V)
100 100
90
80 3.0VF
90
Code 26
80
70 70
60 60
50
3.5VF
50
Code 28 Code 32
40 40
30
2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
30
2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
Input Voltage (V)
Input Voltage (V)
Efficiency vs. Input Voltage
(D1-D2 = 3.5V, D3-D4 = 3.2V)
100
90 Code 26
80
70
60
50
40 Code 28 Code 32
30
2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2
Input Voltage (V)
3140.2007.03.1.3
5
5 Page 
AAT3140
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Applications Information
Constant Current Output Level Settings
The constant current source amplitudes for D1 to D4
are set via the serial interface according to a loga-
rithmic scale where each code is 1dB greater than
the previous code. In this manner, LED brightness
appears linear with each increasing code count.
Because the outputs D1 to D4 are true independent
constant current sources, the voltage observed on
any single given output will be determined by the
actual forward voltage (VF) for the LED being driven.
Since the output current of the AAT3140 is pro-
grammable, no PWM (pulse width modulation) or
additional control circuitry are needed to control
1.00
LED brightness. This feature greatly reduces the
burden on a microcontroller or system IC to manage
LED or display brightness, allowing the user to "set
it and forget it." With its high-speed serial interface
(1MHz data rate), the output current of the AAT3140
can be changed successively to brighten or dim
LEDs in smooth transitions (e.g., to fade out) or in
abrupt steps, giving the user complete programma-
bility and real-time control of LED brightness.
The individual current level settings are each
approximately 1dB apart for settings above Code 8
(see Figure 1). The current level settings below
Code 8 are more than 1dB apart and serve the
needs for transmissive displays and other low-cur-
rent applications.
0.10
0.01
0.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Code
Figure 1: Normalized Current Level Settings.
Code
1
2
3
4
5
6
7
8
IOUT (typ)
(mA)
0.0
0.1
0.2
0.4
0.5
0.7
1.1
1.8
Code
9
10
11
12
13
14
15
16
IOUT (typ)
(mA)
2.0
2.2
2.5
2.8
3.2
3.5
4.0
4.5
Code
17
18
19
20
21
22
23
24
IOUT (typ)
(mA)
5.1
5.6
6
7
8
9
10
12
Code
25
26
27
28
29
30
31
32
IOUT (typ)
(mA)
13
15
17
19
21
24
27
30
Table 1: Constant Current Source Output Nominal Programming Levels.
3140.2007.03.1.3
11
11 Page | ||
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| PDF Descargar | [ Datasheet AAT3140.PDF ] | |
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