PRODUCT DATASHEET
AAT1281
TM
SwitchReg
2A Driver IC for High Intensity LED Camera Flash
General Description
Features
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The AAT1281 is a high efficiency, high current boost con-
verter capable of 2A maximum output current using a
Super Capacitor. It is an ideal power solution for LED
photo flash applications in all single cell Li-ion powered
products.
VIN Range: 2.7V to 5.5V
Dual Channel Output
Up to 2A Regulated Output Current
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1A per channel
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Fixed Input Current Limit
800mA*
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The AAT1281 maintains output current regulation by
switching the internal high-side and low-side switch tran-
sistors. The transistor switches are pulse-width modu-
lated at a fixed frequency of 2MHz. The high switching
frequency allows the use of a small inductor and output
capacitor, making the AAT1281 ideally suited for small
battery-powered applications. A high-capacity Super
Capacitor on the secondary side of the step-up converter
provides the high-peak flash LED current, thereby reduc-
ing peak current demand from the Li-ion battery. To
achieve this, the step-up converter features a fixed input
current limiter. Also included are a “ready to flash” signal,
indicating that the Super Capacitor is sufficiently charged,
and a capacitor balancing pin.
Suited for Super Capacitor Applications
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Super Capacitor Balancing Pin
POK: Ready to Flash Signal
Internal Balancing Resistors
Up to 90% Efficiency
2MHz Switching Frequency
Separate Flash Enable
Single Resistor sets Flash and Movie Mode Current
AS2Cwire Single Wire Interface Sets:
16 Level Movie Mode Current
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Flash/Movie Current Ratio
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Current Output Channel Control
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Safety Timer
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Supply Current in Shutdown: <1.0ꢀA
True Load Disconnect
AnalogicTech’s AS2Cwire™ (Advanced Simple Serial
Control™) serial digital input is used to enable, disable
and set the movie mode current for each LED with 16
level settings. It includes a separate Flash Enable input
to both initiate the Flash current and also start a default
timer (also programmable) used either to terminate the
Flash pulse at end of a predetermined time or as a
safety feature.
Small Application Circuit
Automatic Soft-Start
ꢀ 14-pin TDFN3x3 Package
-40°C to +85°C Temperature Range
Applications
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Camcorder Video Light (Torch Light)
Camera Phones/Smartphones
Digital Still Cameras (DSCs)
LED Photo Flash Light (Strobe Light)
Mobile Handsets
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 AAT1281; in the case of
two LEDs the output current is matched between each
diode. The ratio of maximum flash current to movie mode
current can also be adjusted via the AS2Cwire control.
The AAT1281 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 1.0ꢀA.
The AAT1281 is available in a Pb-free, thermally
enhanced 14-pin 3x3mm TDFN package.
* Contact Sales for alternative current limits.
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