AAT3123/23A/24
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3123.2005.12.1.4
1
ChargePump
TM
General Description
The AAT3123/23A/24 is a low noise, constant fre-
quency charge pump DC/DC converter that uses a
dual mode load switch (1X) and fractional (1.5X)
conversion to maximize efficiency for white LED
applications. The device can be used to produce
current levels up to 20mA to drive up to six LEDs
from a 2.7V to 5.5V input. Outputs may be operat-
ed individually or paralleled for driving higher-cur-
rent LEDs. A low external parts count (two 1
F fly-
ing capacitors and two small 1
F capacitors at V
IN
and OUT) make the AAT3123/23A/24 ideally suited
for small battery-powered applications.
AnalogicTech's Simple Serial ControlTM (S
2
CwireTM)
interface is used to enable, disable, and set the
LED drive current with a 32-level logarithmic scale
LED brightness control. The AAT3123/23A/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 circuitry 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 quies-
cent current to less than 1
A. The device also inte-
grates a test current/auto-disable feature for each
channel. The AAT3123/23A is available in a very
small, Pb-free 12-pin TSOPJW package. The six
output AAT3124 is available in a Pb-free 16-pin
4x4mm QFN package.
Features
V
IN
Range: 2.7V to 5.5V
Dual Mode 1X and 1.5X Charge Pump for
Maximum Efficiency
Drives Low-V
F
and High-V
F
Type LEDs
Up to Six 20mA Outputs (AAT3124)
Up to Four 20mA Outputs (AAT3123/23A)
32-Position Logarithmic Scale with Digital
Control
Simple Serial Control (S
2
Cwire) Interface
Low Noise Constant Frequency Operation
1MHz Switching Frequency
Small Application Circuit
Regulated Output Current
Automatic Soft Start
No Inductors
I
Q
<1
A in Shutdown
Temperature Range: -40C to +85C
12-Pin TSOPJW Package (AAT3123/23A)
16-Pin 4x4mm QFN Package (AAT3124)
Applications
Color (RGB) Lighting
Programmable Current Source
White LED Backlighting
White Photo Flash for DSCs
Typical Application
C
IN
1
F
V
BATTERY
C
OUT
1
F
EN/SET
C1
1
F
C2
1
F
D6
D5
D4
D3
VIN
VOUT
C1+
C1-
C2+
C2-
D1
D2
D3
D4
EN/SET
GND
AAT3124
D5
D6
D2
D1
AAT3123/23A/24
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
2
3123.2005.12.1.4
Pin Descriptions
Pin Configuration
TSOPJW-12
QFN44-16
(Top View)
(Top View)
1
2
3
4
12
11
10
9
5
6
7
8
16
15
14
13
D2
D5
D6
D3
D4
C1+
C1-
N/C
OUT
C2+
C2-
GND
AAT3124
N/C
IN
EN/SET
D1
1
2
3
4
5
6
12
11
10
9
8
7
C2+
AAT3123
AAT3123A
OUT
C1-
C1+
D4
D3
C2-
GND
IN
EN/SET
D1
D2
Pin #
AAT3123/23A
AAT3124
(TSOPJW-12)
(QFN44-16)
Symbol
Function
1
10
C2+
Flying capacitor 2 positive terminal. Connect a 1
F capacitor
between C2+ and C2-.
2
9
OUT
Charge pump output. Requires 1
F capacitor connected
between this pin and ground.
3
7
C1-
Flying capacitor 1 negative terminal.
4
6
C1+
Flying capacitor 1 positive terminal. Connect a 1
F capacitor
between C1+ and C1-.
5
5
D4
Current source output #4.
6
4
D3
Current source output #3.
7
1
D2
Current source output #2.
8
16
D1
Current source output #1.
9
15
EN/SET
Control pin using S
2
Cwire serial interface.
10
14
IN
Input power supply. Requires 1
F capacitor connected between
this pin and ground.
11
12
GND
Ground.
12
11
C2-
Flying capacitor 2 negative terminal.
2
D5
Current source output #5.
3
D6
Current source output #6.
8, 13
N/C
No connection.
EP
Exposed paddle (bottom); connect to GND directly beneath
package.
AAT3123/23A/24
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3123.2005.12.1.4
3
Absolute Maximum Ratings
1
Thermal Information
3
Symbol
Description
Value
Units
JA
Thermal Resistance
QFN44-16 50
TSOPJW-12
160
C/W
P
D
Maximum Power Dissipation
QFN44-16
4
2.0
TSOPJW-12
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
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 20mW/C above 25C.
5. Derate 6.25mW/C above 25C.
AAT3123/23A/24
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
4
3123.2005.12.1.4
Electrical Characteristics
1
C
IN
= C
OUT
= C
1
= C
2
= 1.0F; T
A
= -40C to +85C, unless otherwise noted. Typical values are T
A
= 25C,
V
IN
= 3.5V.
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 = 3.6V, V
IN
= 3.5V
0.5
%
Two Outputs
VD5:VD6 = 3.6V, 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
= 2.7V to 5.5V
0.5
V
V
EN(H)
Enable Threshold High
V
IN
= 2.7V 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
1. The AAT3123/4 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is
assured by design, characterization, and correlation with statistical process controls.
AAT3123/23A/24
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3123.2005.12.1.4
5
Typical Characteristics
Unless otherwise noted, V
IN
= 3.5V, C
IN
= C
OUT
= C
1
= C
2
= 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
Input Voltage (V)
V
IH
V
IL
Quiescent Current vs. Input Voltage
Input Voltage (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. Input Voltage
(4x10mA)
Input Voltage (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. Input Voltage
(4x20mA)
Input Voltage (V)
I
DIODE
(mA)
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
V
DIODE
= 3.0V
V
DIODE
= 3.2V
V
DIODE
= 3.4V
Efficiency vs. Input Voltage
(4x10mA)
Input Voltage (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. Input Voltage
(4x20mA)
Input Voltage (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
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