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| AAT1270_08 Datasheet, PDF (2/18 Pages) Advanced Analogic Technologies – 1A Step-Up Current Regulator for Flash LEDs | |||
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SwitchRegTM
PRODUCT DATASHEET
AAT1270
1A Step-Up Current Regulator for Flash LEDs
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
EP
Symbol
CT
EN/SET
FLEN
AGND
IN
SW
PGND
OUT
GND
FLINH
FLOUTB
FLGND
FLOUTA
RSET
Function
Flash timer control input. Connect a capacitor between CT and AGND to set maximum duration for the ï¬ash
pulse. A 47nF ceramic capacitor sets the ï¬ash timer to 1s. To disable the ï¬ash timer, connect CT to AGND.
Enable and movie mode serial control input. EN/SET is the S2Cwire programming input to adjust the movie mode
current level to one of 16 different levels based on the maximum current/7.3 set via the RSET pin.
Flash enable pin. A low-to-high transition on the FLEN pin initiates a ï¬ash pulse and starts the ï¬ash timer.
Analog ground pin. Connect AGND to PGND, GND, and FLGND at a single point as close to the AAT1270 as possible.
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 AAT1270
Boost converter switching node. Connect a 1μH inductor between SW and IN.
Power ground pin. Connect PGND to AGND, GND, and FLGND at a single point as close to the AAT1270 as possible.
Power output of the boost converter. Connect a 2.2μF or larger ceramic capacitor from OUT to PGND as close as
possible to the AAT1270. Connect OUT to the anode(s) of the ï¬ash LED(s).
Ground pin. Connect GND to PGND, AGND, and FLGND at a single point as close to the AAT1270 as possible.
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 ï¬ash timer.
Flash output B. Connect cathode of Flash LEDB to FLOUT B. For a single ï¬ash LED, connect FLOUTB and FLOUTA
together. For two ï¬ash LEDs, each output will conduct 50% of the total ï¬ash output current.
Flash ground pin. Connect FLGND to PGND, GND, and AGND at a single point as close to the AAT1270 as possible
Flash output A. Connect cathode of Flash LED A to FLOUTA. For a single ï¬ash LED, connect FLOUTA and FLOUTB
together. For two ï¬ash LEDs, each output will conduct 50% of the total ï¬ash output current.
Flash current setting input. A 162kΩ resistor from RSET to AGND sets the maximum ï¬ash current available
at FLOUTA or FLOUTB to 500mA. Each FLOUTA and FLOUTB channel will conduct 50% of the maximum pro-
grammed current. The AAT1270âs ï¬ash-to-movie-mode ratio is ï¬xed at 7.3.
Exposed paddle (bottom); Connect EP to PGND as close as possible to the AAT1270.
Pin Configuration
STDFN33-14
(Top View)
CT 1
EN/SET 2
FLEN 3
AGND 4
IN 5
SW 6
PGND 7
14 RSET
13 FLOUTA
12 FLGND
11 FLOUTB
10 FLINH
9 GND
8 OUT
2
www.analogictech.com
1270.2008.07.1.5
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