AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
General Description
The AAT3152 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
applications. The AAT3152 is capable of driving
four-channel LEDs from a 2.7V to 5.5V input. The
current sinks may be operated individually or in par-
allel for driving higher-current LEDs. A low external
parts count (two 1µF flying capacitors and two small
1µF capacitors at V
IN
and V
OUT
) makes this part ide-
ally suited for small, battery-powered applications.
AnalogicTech's S
2
Cwire™ (Simple Serial Control™)
serial digital input is used to enable, disable, and
set current for each LED with eight settings (20mA
down to 50µA) including main/sub-display group
control. The AAT3152 consumes extremely low cur-
rent internally (50µA typical) at light load for opti-
mized efficiency.
Each output of the AAT3152 is equipped with built-
in protection for V
OUT
short-circuit and auto-disable
for load short-circuit conditions. Built-in soft-start
circuitry prevents excessive inrush current during
start-up. A low current shutdown feature discon-
nects the load from V
IN
and reduces quiescent cur-
rent to less than 1µA.
The AAT3152 is available in a Pb-free, space-sav-
ing, thermally-enhanced 12-pin 3x3mm TDFN
package.
Features
•
•
ChargePump
™
•
•
•
•
•
•
•
•
•
•
V
IN
Range: 2.7V to 5.5V
Fully Programmable Current with Single Wire
— Eight-Step Current: 20mA to 50µA
— Individual Main-Sub Group Control
— Low I
Q
(50µA) at Light Load
Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and V
F
Coverage
Drives 1-4 Channels of LEDs
No Inductors, Low Noise Operation
1MHz Constant Switching Frequency
Small Application Circuit
Built-In Thermal Protection
Built-In Auto-Disable for Short-Circuit
Automatic Soft Start
I
Q
<1µA in Shutdown
Thermally-Enhanced 3x3mm 12-Pin TDFN
Package
Applications
•
•
•
•
Color (RGB) Lighting
Programmable Current Sinks
White LED Backlighting
White Photo Flash for Digital Still Cameras
Typical Application
2.7V to 5.5V
C
IN
1µF
VIN
C1+
C1
1µF
C1-
C2+
AAT3152
C2-
VOUT
C2
1µF
D1
D2
D3
D4
C
OUT
1µF
EN/SET
EN/SET
D1
D2
D3
GND
D4
3152.2005.08.1.2
1
AAT3152
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
EP
Symbol
D4
EN/SET
C1+
C1-
VOUT
C2+
C2-
VIN
GND
D1
D2
D3
Function
Current sink input #4.
S
2
Cwire serial interface control pin.
Flying capacitor 1 positive terminal. Connect a 1µF capacitor between C1+
and C1-.
Flying capacitor 1 negative terminal.
Charge pump output to drive load circuit. Requires 1µF capacitor connected
between this pin and ground.
Flying capacitor 2 positive terminal. Connect a 1µF capacitor between C2+
and C2-.
Flying capacitor 2 negative terminal.
Input power supply. Requires 1µF capacitor connected between this pin and
ground.
Ground.
Current sink input #1.
Current sink input #2.
Current sink input #3.
Exposed paddle (bottom); connect to GND directly beneath package.
Pin Configuration
TDFN33-12
(TopView)
D4
EN/SET
C1+
C1-
VOUT
C2+
1
2
3
4
5
6
12
11
10
9
8
7
D3
D2
D1
GND
VIN
C2-
2
3152.2005.08.1.2
AAT3152
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
T
LEAD
Description
Input Voltage
EN/SET to GND Voltage
Maximum DC Output Current
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
-0.3 to 6
-0.3 to V
IN
+ 0.3
150
-40 to 150
300
Units
V
V
mA
°C
°C
Thermal Information
3
Symbol
P
D
θ
JA
Description
Maximum Power Dissipation
4
Maximum Thermal Resistance
Value
2.0
50
Units
W
°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 20mW/°C above 25°C.
3152.2005.08.1.2
3
AAT3152
High Efficiency 1X/1.5X/2X Charge Pump
For White LED Applications
Electrical Characteristics
1
C
IN
= C
OUT
= C
1
= C
2
= 1.0µF; T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are T
A
= 25°C, V
IN
= 3.6V.
Symbol
Description
Conditions
Min
2.7
1X Mode, 3.0
≤
V
IN
≤
5.5, Active,
No Load Current
1.5X Mode, 3.0
≤
V
IN
≤
5.5, Active,
No Load Current
2X Mode, 3.0
≤
V
IN
≤
5.5, Active,
No Load Current
50µA Setting, 1X Mode
EN/SET = 0
I
SET
= 20mA, T
A
= 25°C
V
F
:D1:D4 = 3.6V
0.3
1
1.5
50
-10
0.5
150
1
10
Typ
Max
5.5
1
3
3
Units
V
Input Power Supply
V
IN
Operation Range
mA
I
CC
Operating Current
Shutdown Current
I
SINK
Average Current Accuracy
I
(D-Match)
Current Matching Between Any
Two Current Sink Inputs
2, 3
V
TH
1X to 1.5X or 1.5X to 2X Transition
Threshold at Any Current Sink Pin
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
I
SHDN
I
DX
µA
µA
%
%
mV
100
1000
0.4
1.4
0.3
50
75
500
500
1
75
µs
kHz
V
V
µs
ns
µs
µs
µs
µA
-1
1. The AAT3152 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. Current matching is defined as the deviation of any sink current at I
OUT
= 20mA and 2mA.
3. Specification applies only to the tri-mode charge pump.
4
3152.2005.08.1.2
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