AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
General Description
The AAT3141 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 V
IN
and CP) make the AAT3141 ide-
ally suited for small battery-powered applications.
The AAT3141 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.
AnalogicTech's Advanced Simple Serial Control™
(AS
2
Cwire™) digital input is used to enable, disable,
and set the LED drive current with a 32-level logarith-
mic scale LED brightness control. The AAT3141 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 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 V
IN
and reduces quiescent current to
less than 1µA. The AAT3141 is available in the very
small, Pb-free 12-pin TSOPJW package.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
ChargePump
™
V
IN
Range: 2.7V to 5.5V
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives Low-V
F
and High-V
F
Type LEDs
Up to Four 30mA Outputs
AS
2
Cwire Independent 3+1 Output Addressing
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
I
Q
<1µA in Shutdown
12-Pin TSOPJW Package
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sources
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
VIN
C1+
C1
1μF
CP
V
BATTERY
C
IN
1μF
C
CP
1μF
C1-
C2+
C2
1μF
AAT3141
C2-
D1
D2
D3
D4
EN/SET
EN/SET
D4
GND
D3
D2
D1
3141.2007.03.1.3
1
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
Symbol
C2+
CP
C1-
C1+
D3
D2
D4
D1
EN/SET
IN
GND
C2-
Function
Flying capacitor 2 positive terminal. Connect a 1µF capacitor between C2+
and C2-.
Charge pump output. Requires 1µF capacitor connected between this pin and
ground.
Flying capacitor 1 negative terminal.
Flying capacitor 1 positive terminal. Connect a 1µF capacitor between C1+
and C1-.
Current source output #3.
Current source output #2.
Current source output #4.
Current source output #1.
AS
2
Cwire serial interface control pin.
Input power supply. Requires 1µF capacitor connected between this pin and
ground.
Ground.
Flying capacitor 2 negative terminal.
Pin Configuration
TSOPJW-12
(Top View)
C2+
CP
C1-
C1+
D3
D2
1
2
3
4
5
6
12
11
10
9
8
7
C2-
GND
IN
EN/SET
D1
D4
2
3141.2007.03.1.3
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Absolute Maximum Ratings
1
Symbol
V
IN
V
EN/SET
I
OUT
2
T
J
Description
Input Voltage
EN/SET to GND Voltage
Maximum DC Output Current
Operating Junction Temperature Range
Value
-0.3 to 6
-0.3 to V
IN
+ 0.3
150
-40 to 150
Units
V
V
mA
°C
Thermal Information
3
Symbol
P
D
θ
JA
Description
Maximum Power Dissipation
4
Maximum Thermal Resistance
Value
625
160
Units
mW
°C/W
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at condi-
tions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Based on long-term current density limitation.
3. Mounted on an FR4 board.
4. Derate 6.25mW/°C above 25°C.
3141.2007.03.1.3
3
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Electrical Characteristics
1
C
IN
= C
CP
= C
1
= C
2
= 1.0µF; T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= 25°C,
V
IN
= 3.5V.
Symbol
Description
Conditions
Min Typ Max Units
2.7
VD1:D4 = 2.0V, CP = 1X
550
No Load Current, CP = 1.5X
3
V
IN
= 3.5V, EN/SET = 0
V
IN
= 3.5V, T
A
= 25°C
-10
V
IN
= 3.5V, T
A
= 25°C, Code 28 17.1 19
VD1:D4 = 3.6V, V
IN
= 3.5V
-3 ±0.5
V
IN
= 3.5V, I
OUT(TOTAL)
= 120mA,
93
Measured from IN to CP
50
1
V
IN
= 2.7V
V
IN
= 5.5V
0.4
1.4
0.3
50
75
500
500
1
75
5.5
5
1
10
20
3
V
µA
mA
µA
%
mA
%
%
Input Power Supply
V
IN
Operation Range
I
cc
I
SHDN
I
DX
I
(D-Match)
η
CP
Operating Current
Shutdown Current
Output Current Accuracy
2
Current Matching
3
Charge Pump Section Efficiency
Charge Pump Section
T
SS
Soft-Start Time
F
CLK
Clock Frequency
EN/SET
V
EN(L)
Enable Threshold Low
V
EN(H)
Enable Threshold High
T
EN/SET LO
EN/SET Low Time
T
EN/SET HI MIN
Minimum EN/SET High Time
T
EN/SET HI MAX
Maximum EN/SET High Time
T
OFF
EN/SET Off Timeout
T
LAT
EN/SET Latch Timeout
I
EN/SET
EN/SET Input Leakage
µs
MHz
V
V
µs
ns
µs
µs
µs
µA
V
EN/SET
= 5.5V, V
IN
= 5.5V
-1
1. The AAT3141 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured
by design, characterization, and correlation with statistical process controls.
2. Codes 2 through 7 are guaranteed to be within
±15%
of stated current level.
3. Current matching is defined as I
(D-Match)
= (I
D
- I
AVE
)/I
AVE
.
4
3141.2007.03.1.3
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Typical Characteristics
Unless otherwise noted, V
IN
= 3.5V, C
IN
= C
CP
= C
1
= C
2
= 1µF, T
A
= 25°C.
Efficiency vs. Input Voltage
(Code 26)
100
90
100
90
Efficiency vs. Input Voltage
(D1 = 3.5V; D2 = 3.3V; D3 = 3.2V; D4 = 3.0V)
Efficiency (%)
Efficiency (%)
80
70
60
50
40
30
2.9
3.0
3.1
3.0V
F
Code 26
80
70
60
50
40
30
3.5V
F
Code 28
Code 32
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
4.1
4.2
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
Efficiency (%)
80
70
60
50
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
Code 28
Code 32
Input Voltage (V)
3141.2007.03.1.3
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