AAT1271A Datasheet, PDF (1/19 Pages) Advanced Analogic Technologies – 1.5A Step-Up Current Regulator for Flash LEDs

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PROPRIETARY INFORMATION PRODUCT DATASHEET
AAT1271A
1.5A Step-Up Current Regulator for Flash LEDs
General Description
The AAT1271A is a high-efficiency, high-current boost
converter capable of 1.5A typical output current. It is an
ideal power solution for LED photo flash applications in
all single cell Li-ion powered products.
The AAT1271A 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 AAT1271A ideally
suited for small battery-powered applications.
AnalogicTech’s proprietary AS²Cwire™ (Advanced Simple
Serial Control™) serial digital interface is used to enable,
disable, configure, and program the operation of the
AAT1271A. Using the AS²Cwire interface, the movie-
mode current level for each LED, the safety timer delay,
and the flash-to-movie-mode current ratio can be pro-
grammed to one of 16 levels. In addition, the single-wire
serial protocol sets output channel control. The AAT1271A
also includes a separate Flash Enable input to initiate
both the flash operation and the default timer which can
be used either to terminate a flash event at the end of a
user-programmed delay or as a safety feature. Also
included is a Flash Inhibit pin which reduces the flash
current to movie-mode levels during high battery
demand.
The maximum flash and movie-mode current is set by
one external resistor where the ratio of Flash to Movie-
mode current is set at approximately 7.3:1. One or two
LEDs can be connected to the AAT1271A, where in the
case of two LEDs the output current is matched between
each diode.
The AAT1271A contains a thermal management system
to protect the device in the event of an output short-
circuit condition. Built-in circuitry prevents excessive
inrush current during start-up. The shutdown feature
reduces quiescent current to less than 1.0μA.
The AAT1271A is available in a Pb-free, thermally-
enhanced 14-pin 3x3mm TDFN package.
Features
• V_IN Range: 2.7V to 5.5V
• Dual Channel Output
• Up to 1.5A Regulated Output Current (750mA per
channel)
• Up to 85% Efficiency with Small Inductor (1μH)
• 2 MHz Switching Frequency
• Separate Flash Enable
• Separate Flash Inhibit
• User-Programmable Safety Timer
• Single Resistor Sets Flash and Movie Mode Current
• AS²_{Cwire Single Wire Programming:}
▪ Movie Mode Current
▪ ^{Flash/Movie Mode Current Ratio}
▪ Movie Mode Output Configuration
▪ Flash Safety Timer
• True Load Disconnect
• Input Current Limit
• Over-Voltage (Open LED, Open Circuit), Short Circuit,
and Over-Temperature Protection
• Shutdown Current < 1.0μA
• 14-pin TDFN 3x3 mm Package
• -40°C to +85°C Temperature Range
Applications
• Camcorder Video Light (Torch Light)
• Cellphones/Smartphones
• Digital Still Cameras (DSCs)
• LED Photo Flash/Torch
• Mobile Handsets
1271A.2008.07.1.0
www.analogictech.com
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