ChipFind - документация

Электронный компонент: AAT3122

Скачать:  PDF   ZIP
AAT3122
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3122.2004.08.1.2
1
ChargePump
TM
General Description
The AAT3122 is a low noise, constant frequency
charge pump DC/DC converter that uses a dual
mode Load Switch (1X) and fractional (1.5X) con-
version to increase efficiency in White LED appli-
cations. With input voltages ranging from 2.7-5.5
Volts, the device can produce an output current of
up to 120mA. A low external parts count (two 1F
flying capacitors and two small bypass capacitors
at V
IN
and OUT) makes the AAT3122 ideally suited
for small battery-powered applications.
AnalogicTechTM's Simple Serial ControlTM
(S
2
CwireTM) interface is used to enable, disable
and set the LED drive current with a 32 level loga-
rithmic scale LED brightness control. The AAT3122
has a thermal management system to protect the
device in the event of a short circuit condition on
any of the output pins. Built-in soft-start circuitry
prevents excessive inrush current during start-up.
High switching frequency enables the use of small
external capacitors. A low shutdown current feature
disconnects the load from V
IN
and reduces quies-
cent current to less than 1A. The AAT3122 pro-
vides a single current source output that can be
used to drive up to 6 LEDs at 20mA each. The
AAT3122 is available in a TSOPJW-12 package.
Features
V
IN
Range: 2.7V to 5.5V
<1A of Shutdown Current
1 MHz Switching Frequency
Dual Mode 1x and 1.5x Charge Pump for
Maximum Efficiency
Only 4 External components
Simple Serial ControlTM (S
2
Cwire) Interface
Low Noise Constant Frequency Operation
33% Less Input Current Than Doubler Charge
Pumps
Small Application Circuit
Regulated Output Current
Automatic Soft-Start
No Inductors
TSOPJW-12 Package
-40 to +85C Temperature Range
Applications
White LED Backlighting
Programmable Current Source
Typical Application
C
IN
1
F
V
BATTERY
C
OUT
1
F
EN/SET
C1
1
F
C2
1
F
D1
V
IN
V
OUT
C1+
C1-
C2+
C2-
D
EN/SET
GND
AAT3122
D2
D3
D4
D5
D6
AAT3122
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
2
3122.2004.08.1.2
Pin Descriptions
Pin Configuration
TSOPJW-12
1
2
3
4
5
6
12
11
10
9
8
7
C2+
OUT
C1-
C1+
D
D
C2-
GND
IN
EN/SET
D
D
Pin #
Symbol
Function
1
C2+
Flying Capacitor 2 + terminal. Connect a 1.0F Capacitor between C2+ and C2-
2
OUT
Charge pump output. Requires 1.0 F bypass capacitor to ground.
3
C1-
Flying Capacitor 1 - terminal
4
C1+
Flying Capacitor 1 + terminal. Connect a 1.0F Capacitor between C1+ and C1-
5,6,7,8
D
Output current Source with drive capability of up to 120mA.
9
EN/SET
Input Control Pin. Serial data interface that controls the level of output current. See
application information for more details.
10
IN
Input power supply. Requires 1uF bypass capacitor to ground.
11
GND
Ground
12
C2-
Flying Capacitor 2 - terminal
Absolute Maximum Ratings
1
Notes:
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.
Thermal Information
Note 3: Mounted on a FR4 board.
Note 4: Derate 6.25mW/C above 25C.
Symbol
Description
Value
Units
JA
Thermal Resistance
3
160
C/W
P
D
Maximum Power Dissipation (T
A
= 25C)
3, 4
625
mW
Symbol
Description
Value
Units
V
IN
Input Voltage
-0.3 to 6.0
V
V
OUT
Charge Pump Output
-0.3 to 6.0
V
V
EN/SET
EN/SET to GND Voltage
-0.3 to 6.0
V
V
EN/SET(MAX)
Maximum EN/SET to Input Voltage
0.3
V
I
OUT
2
Maximum DC Output Current
150
mA
T
J
Operating Junction Temperature Range
-40 to 150
C
AAT3122
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3122.2004.08.1.2
3
AAT3122
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
4
3122.2004.08.1.2
Electrical Characteristics
1
V
IN
= 3.5V; C
IN
= C
OUT
= C
1
= C
2
= 1.0F; T
A
= -40 to 85C. Unless otherwise noted, typical values are T
A
= 25C
Note 1: The AAT3122 is guaranteed to meet performance specification over the -40 to +85C operating temperature range, and are
assured by design, characterization and correlation with statistical process controls.
Symbol
Description
Conditions
Min
Typ
Max
Units
Input Power Supply
V
IN
Operation Range
2.7
5.5
V
I
cc
Operating Current
3.0
V
IN
5.5, Active,
1.8
3.5
mA
No Load Current
I
SHDN
Shutdown Current
EN = 0
1.0
A
I
D
Max. Output Current
V
IN
= 3.5V; Code = 32
108
120
132
mA
Charge Pump
T
SS
Soft start time
200
s
F
CLK
Clock Frequency
1000
KHz
CP
Charge Pump Efficiency
V
IN
= 3.6, I
OUT(Total)
= 120mA;
93
%
Measured from IN to OUT
EN/SET
V
EN(L)
Enable Threshold Low
V
IN
= 2.7 to 5.5V
0.5
V
V
EN(H)
Enable Threshold High
V
IN
= 2.7 to 5.5V
1.4
V
T
LO
EN/SET low time
0.3
75
s
T
HI
Minimum EN/SET high time
50
ns
T
OFF
EN/SET Off Timeout
500
s
Input Current
EN/SET input leakage
-1.0
1.0
A
AAT3122
High Efficiency 1X/1.5X Fractional Charge
Pump for White LED Applications
3122.2004.08.1.2
5
Typical Characteristics
(unless otherwise noted: V
IN
= 3.6V, C
IN
= C
OUT
= C1 = C2 = 1F, T
A
= 25C)
V
IH
and V
IL
vs. V
IN
0.600
0.625
0.650
0.675
0.700
0.725
0.750
0.775
0.800
0.825
0.850
2.5
3.0
3.5
4.0
4.5
5.0
5.5
V
IN
(V)
V
IH
V
IL
Quiescent Current vs. V
IN
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.50
3.00
3.50
4.00
4.50
5.00
5.50
V
IN
(V)
Quiescent Current (mA)
V
DIODE
= 3.3V
V
DIODE
= 3.4V
V
DIODE
= 3.5V
V
DIODE
= 3.6V
I
DIODE
vs. V
IN
40
45
50
55
60
65
70
75
80
85
90
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
V
IN
(V)
I
DIODE
(mA)
V
DIODE
= 3.3V
V
DIODE
= 3.4V V
DIODE
= 3.5V
V
DIODE
= 3.6V
Efficiency vs. VIN (I
D
= 80mA)
50%
55%
60%
65%
70%
75%
80%
85%
90%
95%
100%
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
V
IN
(V)
Efficiency
V
DIODE
= 3.3V
V
DIODE
= 3.4V
V
DIODE
= 3.5V
V
DIODE
= 3.6V