PRODUCT DATASHEET
AAT1270
SwitchReg
TM
General Description
The AAT1270 is a high-efficiency, high-current boost con-
verter capable of 1A maximum output current. It is an ideal
power solution for LED photo flash applications in all single-
cell Lithium-ion / polymer battery operated products.
The AAT1270 maintains output current regulation by
switching the internal high-side and low-side switch
transistors. The transistor switches are pulse-width
modulated at a fixed frequency of 2MHz. The high
switching frequency allows the use of a small inductor
and output capacitor, making the AAT1270 ideally suited
for small battery-powered applications.
AnalogicTech’s proprietary S
2
Cwire™ (Simple Serial
Control™) serial digital interface is used to enable, dis-
able and set the movie mode current level for the flash
LEDs to one of 16 levels. The AAT1270 also includes a
separate Flash Enable input to initiate both flash/strobe
operation and the default timer, which can be used to
terminate a flash event after a user-programmed delay
or as a safety feature. A Flash Inhibit pin is also includ-
ed which reduces flash current to movie mode level dur-
ing high battery demand.
The maximum flash and movie mode current is set by one
external resistor; the ratio between flash and movie mode
current is set at approximately 7.3:1. One or two LEDs can
be connected to the AAT1270; when two LEDs are used,
the output current is matched between each diode.
The AAT1270 contains over-voltage protection and a
thermal management system to protect the device in the
event of an output open-circuit and short-circuit condi-
tion respectively. Built-in circuitry prevents excessive
inrush current during start-up. The shutdown feature
reduces quiescent current to less than 1.0μA.
The AAT1270 is available in a Pb-free, thermally-enhanced
14-pin 3x3mm STDFN package.
1A Step-Up Current Regulator for Flash LEDs
Features
• Input Voltage Range: 2.7V to 5.5V
• Dual Channel Output
▪
Up to 1A Regulated Output Current (0.5A per
Channel)
• Up to 85% Efficiency with Small Magnetics
• 2 MHz Switching Frequency
• Separate Flash Enable Input
• Separate Flash Inhibit Input
• Single Resistor Sets Flash and Movie Mode Current
▪
Fixed Flash-to-Movie Mode Current Ratio
• 16-Level Movie Mode Current via S
2
Cwire™
• User-Programmable Safety Timer
• True Load Disconnect
• Input Current Limit
• Over-Voltage (Open LED, Open Circuit), Short-Circuit,
and Over-Temperature Protection
• Shutdown Current: < 1.0μA
• Small Inductor Solution: 1μH (0.9mm in height)
• 14-pin STDFN 3x3 Package
• -40 to +85°C Temperature Range
Applications
•
•
•
•
•
•
•
Camcorder Video Light (Torch Light)
Cellphones / Smartphones
Digital Still Cameras (DSC)
LED Photo Flash Light (Strobe Light)
Mobile Handsets
MP3 Players
PDAs and Notebook PCs
Typical Application
L1
1μH
Flash LEDs
Lumiled LXCL-PWF1 or equivalent
IN
SW
OUT
V
BATTERY
C
IN
2.2μF
AAT1270
EN/SET
FLEN
FLINH
RSET
FLOUTA
FLOUTB
CT
C
OUT
2.2μF
Movie Mode
Enable and Set
Flash Enable
Flash Inhibit
R
SET
162kΩ
GND AGND PGND FLGND
C
T
47nF
1270.2008.07.1.5
www.analogictech.com
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
