AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Preliminary Information
3141.2004.07.0.91
1
ChargePump
TM
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 dou-
bling (2X) conversion to maximize efficiency for
White LED applications. The device produces cur-
rent levels up to 30mA on each of its 4 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 high-
er-current LEDs. A low external parts count (two
1F flying capacitors and two small 1F capacitors
at V
IN
, and CP) make the AAT3141 ideally suited
for small battery-powered applications.
Analogic TechTM's Advanced Simple Serial ControlTM
(AS
2
CwireTM) digital input is used to enable, disable
and set the LED drive current with a 32 level loga-
rithmic 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 exces-
sive 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 1A. The AAT3141 is
available in the very small 12 pin TSOPJW package.
Features
Tri Mode 1x, 1.5x, and 2x Charge Pump for
Maximum Efficiency and V
F
coverage
Drives Low-V
F
& High-V
F
Type LEDs
Up to 4, 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
Small Application Circuit
Regulated Output Current
Automatic Soft-Start
V
IN
Range: 2.7V to 5.5V
No Inductors
Iq < 1A in Shutdown
12 pin TSOPJW package
Applications
White LED Backlighting
White Photo-Flash for DSCs
Color (RGB) Lighting
Programmable Current Sources
Typical Application
C
IN
1
F
V
BATTERY
C
CP
1
F
EN/SET
C1
1
F
C2
1
F
D3
D2
D1
V
IN
CP
C1+
C1-
C2+
C2-
D1
D2
D3
D4
EN/SET
GND
AAT3141
D4
Pin Descriptions
Pin Configuration
TSOPJW-12
(Top View)
1
2
3
4
5
6
12
11
10
9
8
7
C2+
CP
C1-
C1+
D3
D2
C2-
GND
IN
EN/SET
D1
D4
Pin #
Symbol
Function
1
C2+
Flying Capacitor 2 + terminal. Connect a 1F capacitor between C2+ and C2-.
2
CP
Charge pump output. Requires 1F capacitor connected between this pin and
ground.
3
C1-
Flying Capacitor 1 - terminal
4
C1+
Flying Capacitor 1 + terminal. Connect a 1F capacitor between C1+ and C1-.
5
D3
Current source output #3
6
D2
Current source output #2
7
D4
Current source output #4
8
D1
Current source output #1
9
EN/SET
AS
2
Cwire Serial Interface Control Pin
10
IN
Input power supply. Requires 1F capacitor connected between this pin and
ground.
11
GND
Ground
12
C2-
Flying Capacitor 2 - terminal
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
2
3141.2004.07.0.91
Absolute Maximum Ratings
Notes:
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.
Thermal Information
Notes:
1. Mounted on a FR4 board.
2. Derate 6.25 mW/C above 25C
Symbol
Description
Value
Units
P
D
Maximum Power Dissipation
1, 2
625
mW
JA
Thermal Resistance
1
160
C/W
Symbol
Description
Value
Units
V
IN
Input Voltage
-0.3 to 6
V
V
EN/SET
EN/SET to GND Voltage
-0.3 to V
IN
+ 0.3
V
I
OUT
2
Maximum DC Output Current
150
mA
T
J
Operating Junction Temperature Range
-40 to 150
C
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
3141.2004.07.0.91
3
Electrical Characteristics
1
C
IN
=C
CP
=C1=C2= 1.0F; T
A
= -40 - 85C unless otherwise noted. Typical values are at T
A
= 25C, V
IN
= 3.5V.
Notes:
1. The AAT3141 is guaranteed to meet performance specification over the -40C to 85C operating temperature range and are assured
by design, characterization and correlation with statistical process controls.
2. Codes 2-7 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
Symbol
Description
Conditions
Min Typ Max Units
Input Power Supply
V
IN
Operation Range
2.7
5.5
V
I
cc
Operating Current
VD1:D4 = 2.0V, CP = 1X
550
A
No Load Current, CP = 1.5X
3
5
mA
I
SHDN
Shutdown Current
V
IN
= 3.5V, EN/SET=0
1
A
I
DX
Output Current Accuracy
2
V
IN
= 3.5V, T
A
= 25C
-10
10
%
I
(D-Match)
Current Matching
3
VD1:D4 = 3.6V, V
IN
= 3.5V
-3
0.5
3
%
CP
Charge Pump Section Efficiency
V
IN
= 3.5V, I
OUT(TOTAL)
= 120mA,
93
%
Measured from IN to CP
Charge Pump Section
T
SS
Soft start time
50
s
F
CLK
Clock Frequency
1
MHz
EN/SET
V
EN(L)
Enable Threshold Low
V
IN
= 2.7V
0.4
V
V
EN(H)
Enable Threshold High
V
IN
= 5.5V
1.4
V
T
EN/SET LO
EN/SET low time
0.3
75
s
T
EN/SET HI MIN
Minimum EN/SET high time
50
ns
T
EN/SET HI MAX
Maximum EN/SET high time
75
s
T
OFF
EN/SET Off Timeout
500
s
T
LAT
EN/SET Latch Timeout
500
s
I
EN/SET
EN/SET input leakage
V
EN/SET
= 5.5V, V
IN
= 5.5V
-1
1
A
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
4
3141.2004.07.0.91
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
3141.2004.07.0.91
5
Typical Characteristics
(Unless otherwise noted, V
IN
= 3.5V, C
IN
= C
CP
= C1 = C2 = 1F, T
A
= 25C)
V
IN
(V)
Efficiency (%)
30
40
50
60
70
80
90
100
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 32
Code 28
Code 26
Efficiency vs. V
IN
D1-D2=3.5V, D3-D4=3.2V
Efficiency vs. V
IN
D1=3.5V, D2=3.3V, D3=3.2V, D4=3.0V
V
IN
(V)
Efficiency (%)
30
40
50
60
70
80
90
100
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 32
Code 28
Code 26
V
IN
(V)
Efficiency (%)
30
40
50
60
70
80
90
100
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
Efficiency vs. V
IN
(Code 26)
3.5V
F
3.0V
F
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