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PDF AAT3142 Data sheet ( Hoja de datos )
| Número de pieza | AAT3142 | |
| Descripción | High Efficiency 1X/1.5X/2X Charge Pump | |
| Fabricantes | AAT | |
| Logotipo |  |
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AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
General Description
Features
ChargePump™
The AAT3142 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-
• VIN Range: 2.7V to 5.5V
• Tri-Mode 1X, 1.5X, and 2X Charge Pump for
mode load switch (1X), fractional (1.5X), and dou-
bling (2X) conversion to maximize efficiency for
white LED applications. The device produces cur-
Maximum Efficiency and VF Coverage
• Drives Low-VF and High-VF Type LEDs
• Up to Three 30mA Outputs
rent levels up to 30mA on each of its three current
• 32-Position Logarithmic Scale with Digital
source outputs to drive various arrangements of
Control
LEDs from a 2.7V to 5.5V input. Outputs may be
• Low Noise Constant Frequency Operation
operated individually or in parallel for driving high-
• 1MHz Switching Frequency
er-current LEDs. A low external parts count (two
• Small Application Circuit
1µF flying capacitors and two small 1µF capacitors
• Regulated Output Current
at VIN and CP) make the AAT3142 ideally suited for
small battery-powered applications.
• Automatic Soft Start
• No Inductors
AnalogicTech's Simple Serial Control™ (S2Cwire™)
digital input is used to enable, disable, and set the
• IQ < 1µA in Shutdown
• 12-Pin TSOPJW Package
LED drive current with a 32-level logarithmic scale
LED brightness control. The AAT3142 has a thermal
management system to protect the device in the
event of a short-circuit condition at an output pin.
Applications
Built-in soft-start circuitry prevents excessive inrush
current during start-up. A high charge pump switch-
• Color (RGB) Lighting
ing frequency enables the use of very small external •www.DataSheet4U.com Programmable Current Sources
capacitors. In shutdown mode, the device discon-
• White LED Backlighting
nects the load from VIN and reduces quiescent cur-
rent to less than 1µA. The AAT3142 is available in
• White Photo Flash for Digital Still Cameras
the very small, Pb-free 12-pin TSOPJW package.
Typical Application
VBATTERY
CIN CCP
1μF 1μF
EN/SET
VIN C1+
CP C1-
C2+
AAT3142
C2-
D1
D2
D3
EN/SET
GND
C1
1μF
C2
1μF
D3 D2 D1
3142.2007.03.1.2
1
1 page  
AAT3142
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)
100
90
80 3.0VF
100
90 Code 26
80
70 70
60 60
Code 32
50
3.5VF
50 Code 28
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 = 3.2V)
100
90 Code 26
80
70
60
50 Code 32
40 Code 28
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)
3142.2007.03.1.2
5
5 Page 
AAT3142
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 D3
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 D3 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 AAT3142 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 AAT3142
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 of 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
Figure 1: Constant Current Source Output Nominal Programming Levels.
3142.2007.03.1.2
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet AAT3142.PDF ] | |
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