AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3123.2003.09.1.1
1
ChargePump
TM
General Description
The AAT3123/24 is a low noise, constant frequen-
cy charge pump DC/DC converter that uses a dual
mode Load Switch (1X) and fractional (1.5X) con-
version to maximize efficiency for White LED appli-
cations. The device can be used to produce current
levels up to 20mA to drive up to 6 LEDs from a
2.7V to 5.5V input. Outputs may be operated indi-
vidually or paralleled for driving higher-current
LEDs. Low external parts counts (two 1
F flying
capacitors and two small 1
F capacitors at V
IN
,
and OUT) make the AAT3123/24 ideally suited for
small battery-powered applications.
AnalogicTechTM's Simple Serial ControlTM
(S
2
CwireTM) interface is used to enable, disable
and set the LED drive current with a 32 level loga-
rithmic scale LED brightness control. The
AAT3123/24 has a thermal management system to
protect the device in the event of a short circuit
condition at the output pin. Built-in soft-start circuit-
ry prevents excessive inrush current during start-
up. A high charge pump switching frequency
enables the use of very small external capacitors.
A low current shutdown feature disconnects the
load from V
IN
and reduces quiescent current to less
than 1
A. The AAT3123 is available in very small
12 pin TSOPJW package. The six output AAT3124
is available in a 16 pin 4x4mm QFN package.
Features
Dual Mode 1x and 1.5x Charge Pump for
Maximum Efficiency
Drives Low-V
F
& High-V
F
Type LEDs
Up to 6 20mA Outputs
32 Position Logarithmic Scale with Digital
Control
Simple Serial ControlTM (S
2
CwireTM) interface
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 < 1
A in Shutdown
Temperature Range -40 to 85C.
16 pin 4x4 QFN package (AAT3124)
12 pin TSOPJW-12 package (AAT3123)
Applications
White LED Backlighting
White Photo-Flash for DSCs
Color (RGB) Lighting
Programmable Current Source
Typical Application
C
IN
1
F
V
BATTERY
C
OUT
1
F
EN/SET
C1
1
F
C2
1
F
D6
D5
D4
D3
V
IN
V
OUT
C1+
C1-
C2+
C2-
D1
D2
D3
D4
EN/SET
GND
AAT3124
D5
D6
D2
D1
AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
2
3123.2003.09.1.1
Pin Descriptions
Pin Configuration
12-Lead TSOPJW
16 LD 4x4mm QFN
(Top View)
(Top View)
C2-
IN
EN/
SET
GND
D1
D2
1
2
3
4
5
6
C1+ C1-
7
8
16
15
14
13
12
11
10
9
NC
OUT
C2+
NC
D5*
D6*
D3
D4
AAT 3124
1
2
3
4
5
6
12
11
10
9
8
7
C1+
C1-
C2+
C2-
IN
OUT
EN/SET
GND
D4
D3
D1
D2
AAT 3123
Pin #
Symbol
Function
AAT3123
AAT3124
(TSOPJW-12)
(16LD 4x4 QFN)
8
16
D1
Current source output #1
7
1
D2
Current source output #2
6
4
D3
Current source output #3
5
5
D4
Current source output #4
2
D5
Current source output #5
3
D6
Current source output #6
4
6
C1+
Flying Capacitor 1 + terminal. Connect a 1
F capaci-
tor between C1+ and C1-.
3
7
C1-
Flying Capacitor 1 - terminal
1
10
C2+
Flying Capacitor 2 + terminal. Connect a 1
F capaci-
tor between C2+ and C2-.
12
11
C2-
Flying Capacitor 2 - terminal
11
12
GND
Ground
2
9
OUT
Charge pump output. Requires 1
F capacitor connect-
ed between this pin and ground.
10
14
IN
Input power supply. Requires 1
F capacitor connected
between this pin and ground.
9
15
EN/SET
Control Pin using S
2
Cwire serial interface.
8, 13
NC
No Connection
Absolute Maximum Ratings
1
Notes:
1: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-
ditions 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
Note 3: Mounted on an FR4 board.
Note 4: Derate 20mW/C above 25C.
Note 5: Derate 6.25mW/C above 25C.
Symbol
Description
Value
Units
JA
Thermal Resistance
3
(QFN-16 package)
50
JA
Thermal Resistance
3
(TSOPJW-12 package)
160
C/W
P
D
Maximum Power Dissipation (QFN-16 package, T
A
= 25C)
3, 4
2
P
D
Maximum Power Dissipation (TSOPJW-12 package, T
A
= 25C)
3, 5
0.625
W
Symbol
Description
Value
Units
V
IN
Input Voltage
-0.3 to 6
V
V
OUT
Charge Pump Output
-0.3 to 6
V
FB,V
EN/SET
FB or EN/SET to GND Voltage
-0.3 to 6
V
V
EN/SET(MAX)
Maximum EN/SET to Input Voltage
0.3
V
I
OUT
2
Maximum DC Output Current
150
mA
T
J
Operating Junction Temperature Range
-40 to 150
C
AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3123.2003.09.1.1
3
AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
4
3123.2003.09.1.1
Electrical Characteristics
1
C
IN
= C
OUT
= C1 = C2 = 1.0F; T
A
= -40 to 85C unless otherwise noted. Typical values are at T
A
= 25C, V
IN
= 3.5V.
Note 1: The AAT3123/4 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.
Symbol
Description
Conditions
Min
Typ
Max Units
Input Power Supply
V
IN
Operation Range
2.7
5.5
V
I
cc
Operating Current
3.0
V
IN
5.5, Active,
1.8
3.5
mA
No Load Current
I
SHDN(MAX)
Shutdown Current
EN=0
1
A
I
DX
Output Current
V
IN
= 3.5V, Code = 32, T
A
= 25C
18
20
22
mA
I
(D-Match)
Current Matching between any
VD1:D4=3.6, V
IN
=3.5V
0.5
%
two outputs
VD5:VD6=3.6, V
IN
=3.5V
0.5
CP
Charge Pump Section Efficiency
V
IN
= 3.5V, I
OUT(TOTAL)
= 120mA,
93
%
Measured from IN to OUT
Charge Pump Section
T
SS
Soft start time
200
s
F
CLK
Clock Frequency
1000
kHz
EN/SET
V
EN(L)
Enable Threshold Low
V
IN
= 2.7 to 5.5V
0.5
V
V
EN(H)
Enable Threshold High
V
IN
= 2.7 to 5.5V
1.4
V
T
EN/SET LO
EN/SET low time
0.3
75
s
T
EN/SET HI
Minumum EN/SET high time
50
ns
T
OFF
EN/SET Off Timeout
500
s
Input Current EN/SET input leakage
-1
1
A
Typical Characteristics
(Unless otherwise noted, V
IN
= 3.5V, C
IN
= C
OUT
= C1 = C2 = 1F, T
A
= 25C)
V
IH
and V
IL
vs. V
IN
0.600
0.625
0.650
0.675
0.700
0.725
0.750
0.775
0.800
0.825
0.850
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V
IN
(V)
Quiescent Current vs. V
IN
V
IN
(V)
Quiescent Current (mA)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
V
DIODE
= 3.0V
V
DIODE
= 3.2V
V
DIODE
= 3.4V
I
DIODE
vs. V
IN
(4x10mA)
V
IN
(V)
I
DIODE
(mA)
35
40
45
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
V
DIODE
= 3.0V
V
DIODE
= 3.2V
V
DIODE
= 3.4V
I
DIODE
vs. V
IN
(4x20mA)
V
IN
(V)
I
DIODE
(mA)
V
DIODE
= 3.0V
V
DIODE
= 3.2V
V
DIODE
= 3.4V
60
65
70
75
80
85
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
Efficiency vs. V
IN
(4x10mA)
V
IN
(V)
Efficiency
50%
55%
60%
65%
70%
75%
80%
85%
90%
95%
100%
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
V
DIODE
= 3.2V
V
DIODE
= 3.4V
V
DIODE
= 3.0V
Efficiency vs. V
IN
(4x20mA)
V
IN
(V)
Efficiency
50%
55%
60%
65%
70%
75%
80%
85%
90%
95%
100%
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
V
DIODE
= 3.0V
V
DIODE
= 3.2V
V
DIODE
= 3.4V
AAT3123/4
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3123.2003.09.1.1
5
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