General Description
The AAT3172 is a high output current, high effi-
ciency, low noise, low profile charge pump DC/DC
converter, ideal for multi-function LED photo-flash
applications where solution cost, size, and efficien-
cy are critical.
The dual charge pump in the AAT3172 is capable
of delivering 600mA peak output current. Two cur-
rent-controlled paths are available for users of dual
flash LEDs that prefer current matching. Each LED
channel can be easily programmed in 32 steps with
a single GPIO output through the AS
2
CwireTM
(Advanced Simple Serial ControlTM) interface. This
allows smooth transitions and flexible adjustment
of brightness in flash or other lighting modes.
The tri-mode (1X/1.5X/2X) operation of the internal
charge pump offers excellent power efficiency for
both flash and movie modes. Combined with a low
external parts count (two 1F flying capacitors and
one small bypass capacitor at V
IN
and OUT), the
AAT3172 is ideally suited for small, battery-powered
applications.
The AAT3172 has a thermal management system to
protect the device in the event of a short-circuit con-
dition at the output pin. Built-in soft-start circuitry
prevents excessive inrush current during start-up.
The shutdown feature disconnects the load from V
IN
and reduces quiescent current to less than 1.0A.
The AAT3172 is available in the Pb-free, thermally-
enhanced, 12-pin 3x3 TDFN package.
Features
V
IN
Range: 2.7V to 5.5V
600mA Peak Output Current
Tri-Mode 1X/1.5X/2X in Current Mode
Voltage Mode Operation: 1.5X, 100mA
Dual Regulated Current Sinks
Current Match Between Current Sinks
32 Current Steps Set by AS
2
Cwire
1F Input, Output, and Flying Capacitors
<1.0A of Shutdown
Small Application Circuit
No Inductors
Automatic Soft Start
12-Pin TDFN 3x3 Package
-40C to +85C Temperature Range
Applications
Camera Phones
Digital Still Cameras (DSCs)
PDAs and Notebook PCs
Smart Phones
AAT3172
High Current LED Flash Driver Charge Pump IC
Typical Application
AAT3172
C
OUT
2.2
F
EN/SET
V
IN
C1+
C1- C2+
C2-
V
OUT
F1
F2
2.7V to 5.5V
EN/SET
Flash
LED 1
Flash
LED 2
GND
C
IN
4.7
F
C1
1
F
C2
1
F
3172.2005.11.1.1
1
ChargePump
TM
Pin Descriptions
Pin Configuration
TDFN33-12
(Top View)
VIN
C1+
C1-
1
GND
F1
F2
VIN
VOUT
C2+
C2-
N/C
EN/SET
2
3
4
5
6
12
11
10
9
8
7
Pin #
Symbol
Function
1, 12
VIN
Input power supply pin. Requires 4.7F bypass capacitor to ground.
2
C1+
Flying capacitor C1 positive terminal. Connect a 1.0F capacitor between C1+ and C1-.
3
C1-
Flying capacitor C1 negative terminal.
4
GND
Ground connection.
5
F1
Current sink input #1.
6
F2
Current sink input #2.
7
EN/SET
AS
2
Cwire serial interface control pin.
8
N/C
No connection.
9
C2-
Flying capacitor C2 negative terminal.
10
C2+
Flying capacitor C2 positive terminal. Connect a 1F capacitor between C2+ and C2-.
11
VOUT
Charge pump output. Requires 2.2F capacitor connected between this pin and ground.
EP
Exposed paddle (bottom); connect to GND directly beneath package.
AAT3172
High Current LED Flash Driver Charge Pump IC
2
3172.2005.11.1.1
Absolute Maximum Ratings
1
T
A
= 25C, unless otherwise noted.
Thermal Information
2
Symbol
Description
Value
Units
JA
Maximum Thermal Resistance
50
C/W
P
D
Maximum Power Dissipation
2.0
W
Symbol
Description
Value
Units
V
IN
Input Voltage
-0.3 to 6.0
V
V
EN
EN to GND Voltage
-0.3 to 6.0
V
V
EN(MAX)
Maximum EN to Input Voltage
V
IN
+ 0.3
V
I
OUT
Maximum DC Output Current (continuous)
400
mA
T
J
Operating Junction Temperature Range
-40 to 150
C
T
S
Storage Temperature Range
-65 to 150
C
T
LEAD
Maximum Soldering Temperature (at leads, 10 sec)
300
C
AAT3172
High Current LED Flash Driver Charge Pump IC
3172.2005.11.1.1
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. Mounted on an FR4 board.
Electrical Characteristics
1
C
IN
= 4.7F, C
OUT
= 2.2F, C
1
= C
2
= 1.0F; T
A
= -40C to +85C, unless otherwise noted. Typical values are
T
A
= 25C, V
IN
= 3.6V.
Symbol
Description
Conditions
Min Typ Max Units
Power Supply
V
IN
Input Voltage Range
2.7
5.5
V
V
OUT(MAX)
Maximum Output Voltage
5.5
V
ON/OFF Standby Mode, Code
10
Address = 4, Data = 2
A
I
CC
Operating Current
1X, No Load Current
300
3.0
V
IN
5.5, 1.5X Mode, No Load Current
2.0
4.0
mA
3.0
V
IN
5.5, 2X Mode, No Load Current
3.0
6.0
I
SHDN(MAX)
V
IN
Pin Shutdown Current
EN = 0
1.0
A
I
OUT(MAX)
2
Maximum Output Current
V
F
= 3.6V
600
mA
I
(D-Match)
Current Matching Between
V
IN
= 3.6V, T
A
= 25C, 428mA
Outputs; High Current
Code Address = 3, Data = 2;
8
%
Code Address = 0, Data = 4
I
(D-Match)
Current Matching Between
V
IN
= 3.6V, T
A
= 25C, 100mA
Outputs; Low Current
Code Address = 3, Data =1;
8
%
Code Address = 0, Data = 1
I
DX
Output Current Accuracy
T
A
= 25C, Code 1, HI Scale
270
330
mA
F
CLK
Clock Frequency
2
MHz
V
REG
Voltage Mode Regulation
EN/SET Code Address = 5, Data = 2
4.1
4.5
4.9
V
T
SS
Soft-Start Time
200
s
EN/SET
V
IL
Enable Threshold Low
V
IN
= 2.7V
0.4
V
V
IH
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
Input Current
EN/SET Input Leakage
-1
1
A
AAT3172
High Current LED Flash Driver Charge Pump IC
4
3172.2005.11.1.1
1. The AAT3172 is guaranteed to meet performance specifications from 0C to 70C. Specification over the -40C to +85C operating
temperature range is assured by design, characterization, and correlation with statistical process controls.
2. Mounted on an FR4 board.
Typical Characteristics
V
IN
= 3.6V, C
IN
= 4.7F, C
OUT
= 2.2F, C
1
= C
2
= 1F, T
A
= 25C, unless otherwise noted.
Turn-Off from 1.5X Mode
(V
IN
= 3.2V; 50mA/ch Load)
200
s/div
EN
(2V/div)
V
F
(1V/div)
I
IN
(200mA/div)
Turn-On to 2X Mode
(V
IN
= 3.2V; 300mA/ch Load)
500
s/div
EN
(2V/div)
V
OUT
(2V/div)
I
IN
(500mA/div)
V
SINK
(1V/div)
Turn-On to 1X Mode
(V
IN
= 4.2V; 300mA/ch Load)
500
s/div
EN
(2V/div)
V
OUT
(2V/div)
I
IN
(500mA/div)
V
SINK
(1V/div)
Turn-On to 1.5X Mode
(V
IN
= 3.2V; 50mA/ch Load)
200
s/div
EN
(2V/div)
V
OUT
(2V/div)
I
IN
(200mA/div)
V
SINK
(1V/div)
Turn-On to 1X Mode
(V
IN
= 4.2V; 50mA/ch Load)
200
s/div
EN
(2V/div)
V
OUT
(2V/div)
I
IN
(200mA/div)
V
SINK
(1V/div)
Efficiency vs. Supply Voltage
Supply Voltage (V)
Efficiency (%)
30
40
50
60
70
80
90
100
2.7 2.8 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
152mA/ch
V
F
= 3.0V
95mA/ch
V
F
= 2.9V
50mA/ch
V
F
= 2.8V
AAT3172
High Current LED Flash Driver Charge Pump IC
3172.2005.11.1.1
5
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