AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
3142.2005.12.1.1
1
ChargePump
TM
General Description
The AAT3142 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 three 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 AAT3142 ideally suited for
small battery-powered applications.
AnalogicTech's Simple Serial ControlTM (S
2
CwireTM)
digital input is used to enable, disable, and set the
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.
Built-in soft-start circuitry prevents excessive inrush
current during start-up. A high charge pump switch-
ing frequency enables the use of very small external
capacitors. In shutdown mode, the device discon-
nects the load from V
IN
and reduces quiescent cur-
rent to less than 1A. The AAT3142 is available in
the very small, Pb-free 12-pin TSOPJW package.
Features
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 Three 30mA Outputs
32-Position Logarithmic Scale with Digital
Control
Low Noise Constant Frequency Operation
1MHz Switching Frequency
Small Application Circuit
Regulated Output Current
Automatic Soft Start
No Inductors
I
Q
< 1A 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
C
IN
1
F
V
BATTERY
C
CP
1
F
EN/SET
C1
1
F
C2
1
F
D3
D2
D1
VIN
CP
C1+
C1-
C2+
C2-
D1
D2
D3
EN/SET
GND
AAT3142
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
GND
Pin #
Symbol
Function
1
C2+
Flying capacitor 2 positive 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 negative terminal.
4
C1+
Flying capacitor 1 positive terminal. Connect a 1F capacitor between C1+
and C1-.
5
D3
Current source output #3.
6
D2
Current source output #2.
7
GND
Ground pin; must be connected to Pin 11.
8
D1
Current source output #1.
9
EN/SET
S
2
Cwire serial interface control pin.
10
IN
Input power supply. Requires 1F capacitor connected between this pin and
ground.
11
GND
Ground pin; must be connected to Pin 7.
12
C2-
Flying capacitor 2 negative terminal.
AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
2
3142.2005.12.1.1
Absolute Maximum Ratings
1
Thermal Information
3
Symbol
Description
Value
Units
P
D
Maximum Power Dissipation
4
625
mW
JA
Thermal Resistance
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
AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
3142.2005.12.1.1
3
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 25C.
Electrical Characteristics
1
C
IN
= C
CP
= C
1
= C
2
= 1.0F; T
A
= -40C to +85C, unless otherwise noted. Typical values are at 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
VD1:D3 = 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:D3 = 3.6V, V
IN
= 3.5V
-3
0.5
3
%
CP
Charge Pump Section Efficiency
V
IN
= 3.5V, I
OUT(TOTAL)
= 90mA,
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
AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
4
3142.2005.12.1.1
1. The AAT3142 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.
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
.
AAT3142
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
3142.2005.12.1.1
5
Typical Characteristics
V
IN
= 3.5V, C
IN
= C
CP
= C
1
= C
2
= 1F, T
A
= 25C, unless otherwise noted.
Input Voltage (V)
Efficiency (%)
Efficiency vs. Input Voltage
(D1-D2 = 3.5V, D3 = 3.2V)
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. Input Voltage
(D1 = 3.5V, D2 = 3.3V, D3 = 3.2V)
Input Voltage (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
Input Voltage (V)
Efficiency (%)
Efficiency vs. Input Voltage
(Code 26)
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
3.5V
F
3.0V
F
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