AAT1271A

1.5A Step-Up Current Regulator for Flash LEDs

PROPRIETARY INFORMATION PRODUCT DATASHEET

2

1271A.2008.07.1.0

www .analogictech.com

AAT1271A

1.5A Step-Up Current Regulator for Flash LEDs

PROPRIETARY INFORMATION PRODUCT DATASHEET

2

1271A.2008.07.1.0

www .analogictech.com

Typical Application

AAT1271A

107kΩ

V

BAT

2.2μF

L1

1μH

IN

SW

OUT

FLOUTA

CT

EN/SET

FLINH

RSET

AGND PGND

FLEN

Movie-mode

Enable and Set

Flash Enable

Flash Inhibit

FLOUTB

FLGND

2.2μF

GND

High Current

Flash LEDs

Pin Descriptions

Pin #

Symbol

Function

1CT

Flash timer control input. Connect a capacitor between CT and AGND to set maximum duration of the flash

pulse. To disable the flash timer, connect CT to AGND.

2

EN/SET

the movie-mode current level; b) program the flash timer based on CT; c) select the Flash-to-Movie-mode

ratio; and d) select FLOUTA and FLOUTB’s output configuration.

3

FLEN

Flash enable pin. A low-to-high transition on the FLEN pin initiates a flash pulse and starts the flash timer.

4

AGND

Analog ground pin. Connect AGND to PGND, GND, and FLGND at a single point as close to the AAT1271A as

possible.

5IN

Power input. Connect IN to the input power supply voltage. Connect a 2.2μF or larger ceramic capacitor

from IN to PGND as close as possible to the AAT1271A

6

SW

Boost converter switching node. Connect a 1μH inductor between SW and IN.

7

PGND

Power ground pin. Connect PGND to AGND, GND, and FLGND at a single point as close to the AAT1271A as

possible.

8

OUT

Power output of the boost converter. Connect a 2.2μF or larger ceramic capacitor from OUT to PGND as

close as possible to the AAT1271A. Connect OUT to the anode(s) of the Flash LED(s).

9

GND

Ground pin. Connect GND to PGND, AGND, and FLGND at a single point as close to the AAT1271A as pos-

sible.

10

FLINH

Flash inhibit pin. FLINH is an active HIGH control input with an internal 200kΩ resistor to AGND. A low-to-

high transition on the FLINH pin reduces FLOUTA and FLOUTB output currents to the maximum (default)

movie-mode current level for the duration of FLINH. Strobing the FLINH pin low to high does not reset the

flash timer.

11

FLOUTB

Flash Output B. Connect cathode of Flash LEDB to FLOUTB. For a single flash LED, connect FLOUTB &

FLOUTA together. For two flash LEDs, each output will conduct 50% of the total flash output current.

12

FLGND

Flash ground pin. Connect FLGND to PGND, GND, and AGND at a single point as close to the AAT1271A as

possible

13

FLOUTA

Flash Output A. Connect cathode of Flash LEDA to FLOUTA. For a single flash LED, connect FLOUTA and

FLOUTB together. For two flash LEDs, each output will conduct 50% of the total flash output current.

14

RSET

Flash current setting input. A 107kΩ resistor from RSET to AGND sets the maximum flash current avail-

able at FLOUTA and FLOUTB to 1.5A. Each FLOUTA and FLOUTB channel will conduct 50% of the maximum

programmed current. The AAT1271A’s flash-to-movie-mode ratio is fixed at 7.3:1.

EP

Exposed paddle (bottom); Connect EP to PGND as close as possible to the AAT1271A.