PRODUCT DATASHEET
AAT1239-1
SwitchRegTM
40V Step-Up Converter for 4 to 10 White LEDs
General Description
Features
The AAT1239-1 is a high frequency, high efficiency con-
stant current boost converter capable of driving up to
ten (10) series-connected white LEDs or 40V. It is an
ideal power solutions for backlight applications with up
to ten white LEDs in series. The input voltage is 2.7V to
5.5V for single-cell lithium-ion/polymer (Li-ion) based
portable devices.
• Input Voltage Range: 2.7V to 5.5V
• Maximum Continuous Output 40V @ 30mA
• Drives up to 10 LEDs in Series
Constant LED Current with 3.5% Accuracy Over
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Temperature and Input Voltage Range
• Digital Control with S2Cwire Single Wire Interface
26 Discrete Steps
No PWM Control Required
No Additional Circuitry
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The LED current is digitally controlled across a 6x oper-
ating range using AnalogicTech’s Simple Serial Control™
(S2Cwire™) interface. Programmability across 26 dis-
crete current steps provides high resolution, low noise,
flicker-free, constant LED outputs. In programming
AAT1239 operation, LED brightness increases based on
the data applied at the EN/SET pin. The SEL logic pin
changes the feedback voltage between two program-
mable ranges.
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• Up to 85% Efficiency
• Up to 2MHz Switching Frequency Allows Small External
Chip Inductor and Capacitors
• Hysteretic Control
No External Compensation Components
Excellent Load Transient Response
High Efficiency at Light Loads
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• Integrated Soft Start with No External Capacitor
• True Load Disconnect Guarantees <1.0μA Shutdown
Current
The AAT1239-1 features a high current limit and fast,
stable transitions for stepped or pulsed current applica-
tions. The high switching frequency (up to 2MHz) pro-
vides fast response and allows the use of ultra-small
external components, including chip inductors and
capacitors. Fully integrated control circuitry simplifies
design and reduces total solution size. The AAT1239-1
offers a true load disconnect feature which isolates the
load from the power source while in the OFF or disabled
state. This eliminates leakage current, making the devic-
es ideally suited for battery-powered applications.
• SelectableFeedbackVoltageRangesforHighResolution
Control of Load Current
• Short-Circuit, Over-Voltage, and Over-Temperature
Protection
• 12-Pin TSOPJW Package
• -40°C to +85°C Temperature Range
Applications
The AAT1239-1 is available in the Pb-free, thermally-
enhanced 12-pin TSOPJW package.
• Color Display Backlight
• Digital Still Cameras (DSCs)
• Digital Photo Frames
• PDAs and Notebook PCs
• White LED Drivers
Typical Application
DS1
L1
2.2μH
SS16L or equivalent
LIN
SW
PVIN
VIN
C2
2.2μF
M673
C1
2.2μF
Li-Ion:
= 2.7V to 4.2V
R2
374k
V
IN
AAT1239-1
OVP
R3
12k
Enable/Set
EN/SET
SEL
Feedback Voltage
Select
FB
PGND AGND
ILED
20mA
R1 (RBALLAST
30.1
)
White LEDs
OSRAM LW M678
or equivalent
w w w . a n a l o g i c t e c h . c o m
1239-1.2008.10.1.2
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