PRODUCT DATASHEET
AAT3194
ChargePump
TM
High Efficiency 1.5X Fractional Charge Pump For White LED Applications
Features
• V
IN
Range: 2.7V to 5.5V
• 20mA Full-Scale Current
• Simple Serial Control (S
2
Cwire) Interface
▪
32-Position Logarithmic Scale with Digital Control
• Low Noise Constant Frequency Operation
• 33% Less Input Current Than Doubler Charge Pump
• High Accuracy Brightness Matching
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• 600kHz Switching Frequency
• I
Q
<1µA in Shutdown
• Temperature Range: -40°C to 85°C
• 12-Pin TSOPJW Package
General Description
The AAT3194 is a low noise, constant frequency charge
pump DC/DC converters that use fractional (1.5X) conver-
sion to increase efficiency in white LED applications. The
devices can be used to produce current levels up to 20mA
for each output from a 2.7V to 5.5V input. A low external
parts count (two 1µF flying capacitors and two small
bypass capacitors at IN and OUT) makes these devices
ideally suited for small, battery-powered applications.
AnalogicTech’s Simple Serial Control™ (S
2
Cwire™) inter-
face is used to enable, disable, and set the LED drive
current for 32-level logarithmic scale LED brightness
control. The AAT3194 has a thermal management sys-
tem for protection in the event of a short-circuit condi-
tion on any of the output pins. Built-in soft-start circuitry
prevents excessive inrush current during start-up. A high
switching frequency enables the use of small external
capacitors. A low-current shutdown feature disconnects
the load from V
IN
and reduces quiescent current to less
than 1µA. The AAT3194 is available in a Pb-free 12-pin
TSOPJW package.
Applications
• Programmable Current Source
• White LED Backlighting
Typical Application
IN
C1+
C1
1µF
OUT
V
BATTERY
C
IN
1µF
C
OUT
1µF
C1-
C2+
C2
1µF
AAT3194
C2-
D1
D2
D3
EN/SET
EN/SET
GND
D4
D4
D3
D2
D1
3194.2008.05.1.1
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1
PRODUCT DATASHEET
AAT3194
ChargePump
TM
High Efficiency 1.5X Fractional Charge Pump For White LED Applications
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
Symbol
C2+
OUT
C1-
C1+
D4
D3
D2
D1
EN/SET
IN
GND
C2-
Function
Flying capacitor 2 positive terminal. Connect a 1µF ceramic capacitor between C2+ and C2-.
Charge pump output. Requires 1µF bypass capacitor to ground.
Flying capacitor 1 negative terminal.
Flying capacitor 1 positive terminal. Connect a 1µF ceramic capacitor between C1+ and C1-.
Current source output 4. If not used, leave pin
fl
oating.
Current source output 3. If not used, leave pin
fl
oating.
Current source output 2. If not used, leave pin
fl
oating.
Current source output 1. Required reference current source. Do not leave pin
fl
oating.
Control pin using S
2
Cwire serial interface.
Input power supply. Requires 1µF or larger ceramic capacitor to ground.
Ground.
Flying capacitor 2 negative terminal.
Pin Configuration
TSOPJW-12
(Top View)
C2+
OUT
C1-
C1+
D4
D3
1
2
3
4
5
6
12
11
10
9
8
7
C2-
GND
IN
EN/SET
D1
D2
2
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3194.2008.05.1.1
PRODUCT DATASHEET
AAT3194
ChargePump
TM
High Efficiency 1.5X Fractional Charge Pump For White LED Applications
Absolute Maximum Ratings
T
A
= 25°C, unless otherwise noted.
Symbol
V
IN
V
OUT
V
EN/SET
V
EN/SET(MAX)
I
OUT
T
J
Description
Input Voltage
Charge Pump Output
EN/SET to GND Voltage
Maximum EN/SET to Input Voltage
Maximum DC Output Current (sum of I
OUT
and D currents)
Operating Junction Temperature Range
Value
-0.3 to 6
-0.3 to 6
-0.3 to 6
0.3
120
-40 to 150
Units
V
V
V
V
mA
°C
Thermal Information
1
Symbol
θ
JA
P
D
Description
Thermal Resistance
Maximum Power Dissipation
2
Value
160
625
Units
°C/W
mW
1. Mounted on an FR4 board.
2. Derate 6.25mW/°C above 25°C.
3194.2008.05.1.1
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3
PRODUCT DATASHEET
AAT3194
ChargePump
TM
High Efficiency 1.5X Fractional Charge Pump For White LED Applications
Electrical Characteristics
V
IN
= 3.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= 25°C.
Symbol
Description
Conditions
Min
2.7
Active, No Load Current
EN = 0V
3.0V
≤
V
IN
≤
5.5V, T
A
= 25°C, All Outputs Max Current
3.0V
≤
V
IN
≤
5.5V
VD1:Dn = 3.6V, V
IN
= 3.3V
V
IN
= 3.5V, I
OUT(total)
= 40mA
3
1
24
3
Typ
Max
Units
V
mA
µA
mA
%/V
%
%
µs
kHz
Input Power Supply
Operation Range
V
IN
I
CC
Operating Current
I
SHDN
Shutdown Current
I
DX
Output Current
∆I
D
/∆V
IN
Output Current Line Regulation
Current Matching Between Any
I
(D-Match)
Two Outputs
η
Efficiency
Charge Pump
t
SS
Soft-Start Time
F
CLK
Clock Frequency
EN/SET
Enable Threshold Low
V
EN(L)
V
EN(H)
Enable Threshold High
t
LO
EN/SET Low Time
Minimum EN/SET Regulation
t
HI
t
OFF
EN/SET Off Timeout
Input
EN/SET Input Leakage
Current
16
-3
20
0.3
93
400
300
V
IN
= 2.7V to 5.5V
V
IN
= 2.7V to 5.5V
0.5
1.4
0.3
50
500
V
IN
= 5.5V
-1
1
75
V
V
µs
ns
µs
µA
4
www.analogictech.com
3194.2008.05.1.1
PRODUCT DATASHEET
AAT3194
ChargePump
TM
High Efficiency 1.5X Fractional Charge Pump For White LED Applications
Typical Characteristics
V
IN
= 3.5V, C
IN
= C
OUT
= C
1
= C
2
= 1µF; T
A
= 25°C, unless otherwise noted.
Quiescent Current vs. Temperature
1.00
0.98
0.96
100
95
Efficiency vs. Supply Voltage
30mA
20mA
Efficiency (%)
90
85
80
75
70
65
60
I
Q
(mA)
0.94
0.92
0.90
0.88
0.86
-40
-20
0
20
40
60
80
100
40mA
80mA
60mA
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
Temperature (°C)
Supply Voltage (V)
Quiescent Current vs. Supply Voltage
1.2
1.1
1.0
96
94
Efficiency vs. Load Current
Efficiency (%)
92
90
88
86
84
82
80
0
20
40
60
80
I
Q
(mA)
0.9
0.8
0.7
0.6
3.0
3.5
4.0
4.5
5.0
5.5
Supply Voltage (V)
Load Current (mA)
Shutdown Current vs. Temperature
Shutdown Current (µA)
1.000
710
700
690
0.100
680
670
660
650
640
630
0.001
-40
620
-20
0
20
40
60
80
100
610
-40
Oscillator Frequency vs. Temperature
0.010
F
OSC
(kHz)
Temperature (°C)
-20
0
20
40
60
80
100
Temperature (°C)
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5
