AAT2801
Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
2801.2006.04.1.3
1
ChargePump
TM
General Description
The AAT2801 is a member of AnalogicTech's Total
Power Management ICTM (TPMICTM) product family.
It has a dual charge pump architecture designed to
support both the white LED backlight and flash appli-
cations for systems operating with Lithium-Ion bat-
teries. The backlight charge pump provides power
required to drive up to four LEDs. To maximize
power efficiency, it automatically selects 1X, 1.5X, or
2X mode. The device produces current levels up to
30mA on each of its four current source outputs.
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 flash charge pump is a charge pump doubler
with a regulated output voltage. It is designed to
deliver 120mA of continuous current and up to
250mA of pulsed current. It has an independent
enable pin for improved power savings.
The AAT2801 is equipped with AnalogicTech's
AutoBiasTM technology which allows individual LEDs
to be powered either by charge pump or battery
input, determined internally and automatically to
maximize the power efficiency even with a large dif-
ference in LED forward voltage.
The AAT2801 has thermal protection and built-in
soft-start circuitry. A high charge pump switching fre-
quency enables the use of very small external capac-
itors. The AAT2801 is available in the 16-pin
TDFN44 package.
Features
V
IN
Range: 2.7V to 5.5V
Dual Charge Pump
-- Flash: Charge Pump Doubler
-- Backlight: Tri-Mode Charge Pump
Drives Low-V
F
and High-V
F
LEDs
Up to Four 30mA Outputs
32-Position Logarithmic Scale with Digital
Control
Low Noise Constant Frequency Operation
1MHz Switching Frequency
AutoBias Technology
Regulated 4.5/5.0 Volts V
OUT_FLASH
Up to 250mA of Current for Flash
Automatic Soft Start
No Inductors
I
Q
<1A in Shutdown
Available in 16-pin TDFN44 Package
Applications
Display Modules
Mobile Phones
PDAs
Smart Phones
Typical Application
AAT2801
C
IN
1
F
V
IN
C
CP
1
F
EN/SET
C1
1
F
D3
D2
D1
IN
CP
C1
+
C1
-
D2
GND
D4
Backlight
Flash LED
C2
1
F
C3
1
F
C2
+
C2
-
C3
+
C3
-
OUT_FLSH
C
F
R
B
1
F
Flash Enable
EN/SET
EN_FLSH
D1
D3
D4
Pin Descriptions
Pin Configuration
TDFN44-16
(Top View)
C3-
C3+
OUT_FLASH
1
IN
C1+
C1-
CP
C2+
D4
D2
EN_FLSH
D1
D3
EN/SET
GND
C2-
8
5
6
7
2
3
4
10
16
15
14
13
12
11
9
Pin #
Symbol
Function
1
C3-
Flying capacitor 3 negative terminal. Connect a 1F capacitor between C3- and C3+.
2
C3+
Flying capacitor 3 positive terminal.
3
OUT_FLASH
Flash output voltage. Requires 1F capacitor connected between this pin and ground.
4
IN
Input power supply. Requires 1F capacitor connected between this pin and ground.
5
C1+
Flying capacitor 1 positive terminal. Connect a 1F capacitor between C1+ and C1-.
6
C1-
Flying capacitor 1 negative terminal.
7
CP
White LED charge pump output. Requires 1F capacitor connected between this pin
and ground.
8
C2+
Flying capacitor 2 positive terminal. Connect a 1F capacitor between C2+ and C3-.
9
C2-
Flying capacitor 2 negative terminal.
10
GND
Ground.
11
EN/SET
S
2
Cwire serial interface control pin for the white LED charge pump. This pin should not
be left floating.
12
D3
Current source output #3.
13
D1
Current source output #1.
14
D4
Current source output #4.
15
D2
Current source output #2.
16
EN_FLSH
Active high enable pin for the flash charge pump. When connected low, the charge
pump shuts down and consumes less than 1A of current.
EP
Exposed paddle (bottom); connect to GND directly beneath package.
AAT2801
Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
2
2801.2006.04.1.3
Absolute Maximum Ratings
1
Thermal Information
Symbol
Description
Value
Units
P
D
Maximum Power Dissipation
3, 4
2.0
mW
JA
Thermal Resistance
3
50
C/W
Symbol
Description
Value
Units
V
IN
Input Voltage
-0.3 to 6.0
V
V
EN/SET
EN/SET to GND Voltage
-0.3 to V
IN
+0.3
V
I
OUT
2
Maximum DC Output Current
120
mA
T
J
Operating Junction Temperature Range
-40 to 150
C
AAT2801
Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
2801.2006.04.1.3
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
F
= C1 = C2 = C3 = 1.0F; T
A
= -40C to 85C, unless otherwise noted.
Symbol
Description
Conditions
Min Typ Max Units
Input Power Supply
V
IN
Operation Range
2.7
5.5
V
3.0
V
IN
5.5, No Load Current; V
OUT_FLSH
-
3.0
4.5
= 5V, EN/SET = GND, EN_FLSH = V
IN
I
CC
Operating Current
3.0
V
IN
5.5, EN/SET = V
IN
, EN_FLSH =
0.55
mA
GND, VD1:VD4 = 2.0V, CP = 1X
3.0
V
IN
5.5, No Load Current; EN/SET =
-
3.0
5.0
V
IN
, EN_FLSH = GND, CP = 1.5X
I
SHDN
Shutdown Current
EN_FLSH = EN/SET = 0
-
1.0
A
I
DX
Output Current Accuracy
2
V
IN
= 3.5, Code = 32, T
A
= 25C
-10
10
%
I
(D-Match)
Current Matching
3
VD1:D4 = 3.6, V
IN
= 3.5V; LED Charge
-3.0 0.5
3.0
%
Pump Only
V
OUT
Flash Charge Pump Output
3.0V < V
IN
< 5V, I
OUT
= 120mA;
4.3
4.5
4.7
V
Voltage
EN_FLSH = V
IN
I
OUT
Maximum Continuous I
OUT
V
IN
= 3.6V; V
OUT
= 4.5V; EN_FLSH = V
IN
120
-
mA
Maximum Pulsed I
OUT
V
IN
= 3.6V; V
OUT
= 4.5V; I
Pulsed
< 500mS
250
-
CP
White LED Charge Pump
V
IN
= 3.5V, I
OUT(TOTAL)
= 120mA,
93
%
Section Efficiency
Measured from IN to CP
Charge Pump Section
T
SS
Soft-Start Time
Backlight Charge Pump
50
s
Flash Charge Pump
200
F
CLK
Clock Frequency
1.0
MHz
EN/SET
V
EN(L)
Enable Threshold Low
-
0.4
V
V
EN(H)
Enable Threshold High
1.4
-
V
T
EN/SET LO
EN/SET Low Time
V
EN/SET
< 0.6V
0.3
75
s
T
EN/SET HI MIN
Minimum EN/SET High Time V
EN/SET
> 1.4V
50
s
T
EN/SET HI MAX
Maximum EN/SET High Time V
EN/SET
> 1.4V
-
75
s
T
OFF
EN/SET Off Timeout
V
EN/SET
< 0.6V
-
500
s
T
LAT
EN/SET Latch Timeout
V
EN/SET
> 1.4V
-
500
s
I
EN/SET/EN_FLSH
Input Leakage
V
EN/SET/EN_FLSH
= 5V, V
IN
= 5V
-1.0
1.0
A
AAT2801
Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
4
2801.2006.04.1.3
1. The AAT2801 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
.
Typical CharacteristicsWhite LED Backlight Driver Section
V
IN
= 3.5V, C
IN
= 2.2F, C
CP
= C1 = C2 = 1.0F; T
A
= 25C, unless otherwise noted.
Operating Current
(Code 23; EN_FLSH On; I
OUT
= 100mA)
Input Voltage (V)
I
IN
(A)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
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 5.3 5.5
V_D
X
= 3.3V
V_D
X
= 3.0V
Operating Current
(Code 23; EN_FLSH Off)
Input Voltage (V)
I
IN
(A)
0.0
1.0
2.0
3.0
4.0
5.0
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 5.3 5.5
V_D
X
= 3.3V
V_D
X
= 3.0V
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
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)
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 (%)
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
AAT2801
Multi-Mode Charge Pump for
White LED Backlight and Flash Applications
2801.2006.04.1.3
5
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