PRODUCT DATASHEET
AAT1270
SwitchReg
TM
Pin Descriptions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
EP
1A Step-Up Current Regulator for Flash LEDs
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
fl
ash
pulse. A 47nF ceramic capacitor sets the
fl
ash timer to 1s. To disable the
fl
ash timer, connect CT to AGND.
Enable and movie mode serial control input. EN/SET is the S
2
Cwire 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
fl
ash pulse and starts the
fl
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
fl
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
fl
ash timer.
Flash output B. Connect cathode of Flash LEDB to FLOUT B. For a single
fl
ash LED, connect FLOUTB and FLOUTA
together. For two
fl
ash LEDs, each output will conduct 50% of the total
fl
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
fl
ash LED, connect FLOUTA and FLOUTB
together. For two
fl
ash LEDs, each output will conduct 50% of the total
fl
ash output current.
Flash current setting input. A 162kΩ resistor from RSET to AGND sets the maximum
fl
ash current available
at FLOUTA or FLOUTB to 500mA. Each FLOUTA and FLOUTB channel will conduct 50% of the maximum pro-
grammed current. The AAT1270’s
fl
ash-to-movie-mode ratio is
fi
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
EN/SET
FLEN
AGND
IN
SW
PGND
1
2
3
4
5
6
7
14
13
12
11
10
9
8
RSET
FLOUTA
FLGND
FLOUTB
FLINH
GND
OUT
2
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1270.2008.07.1.5
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