PRODUCT DATASHEET
AAT1239-1
SwitchRegTM
40V Step-Up Converter for 4 to 10 White LEDs
DS1
L1
2.2μH
D1
LED
D6
VCC
LED
D2
LED
JP1
U1
R2
10K
R4
D7
LED
1
2
3
4
5
6
12
11
10
9
8
7
374K
D3
LED
1
2
3
VIN
LIN
OVP
FB
EN
D8
LED
SEL
VP
C1
2.2μF
R3
12K
D4
LED
GND
PGND
SW
Enable
JP2
C2
2.2μF
N/C
SW
D9
LED
D5
LED
1
2
3
AAT1239-1 TSOP12JW
D10
LED
R1
Select
30.1
C1 10V 0603 X5R 2.2μF GRM188R60J225KE01D
C2 50V 1206 X7R 2.2μF GRM31CR71H225KA88
L1 2.2μH SD3814-2R2 or SD3110-2R2
DS1 SS16L
D1-D10 LW M673 White LED
other alternatives:
more stability at 40V: C2 50V 1206 X7R 4.7μF GRM31CR71H475K
under 20V application: C2 25V 0805 X7R 2.2μF GRM21BR71E225KA73L
Figure 4: AAT1239-1 White LED Boost Converter Schematic.
LED Brightness Control
25
20
15
10
5
The AAT1239-1 uses S2Cwire programming to control
LED brightness and does not require PWM (pulse width
modulation) or additional control circuitry. This feature
greatly reduces the burden on a microcontroller or sys-
tem IC to manage LED or display brightness, allowing
the user to “set it and forget it.” With its high-speed
serial interface (1MHz data rate), the output current of
the AAT1239-1 can be changed successively to brighten
or dim the LEDs in smooth transitions (i.e., to fade out)
or in abrupt steps, giving the user complete program-
mability and real-time control of LED brightness.
SEL=HIGH
Default
SEL=LOW
0
1
4
7
10
13
16
S2Cwire Data Register
Figure 5: Programming AAT1239-1 LED Current
with RBALLAST = 30.1Ω.
w w w . a n a l o g i c t e c h . c o m
1239-1.2008.10.1.2
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
