AAT1239-1_0810 Datasheet, PDF (13/23 Pages) Advanced Analogic Technologies – 40V Step-Up Converter for 4 to 10 White LEDs

SwitchReg^TM
VCC
C1
2.2μF
JP1
1
2
3
Enable
JP2
1
2
3
Select
R4 10K
PRODUCT DATASHEET
AAT1239-1
40V Step-Up Converter for 4 to 10 White LEDs
U1
1 _VIN
2 _EN
3 _SEL
4 _VP
5 _N/C
6 _SW
LIN ¹²
OVP ¹¹
FB ¹⁰
GND ⁹
PGND ⁸
SW ⁷
AAT1239-1 TSOP12JW
L1
2.2μH
R1
30.1
DS1
D6
LED
R2
D7
374K _LED
R3
12K
D8
LED
D9
LED
D10
LED
D1
LED
D2
LED
D3
LED
D4
LED
C2
2.2μF
D5
LED
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
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.
25
20
15
Default
SEL=HIGH
10
SEL=LOW
5
0
1
4
7
10
13
16
S²Cwire Data Register
Figure 5: Programming AAT1239-1 LED Current
with R_BALLAST = 30.1Ω.
1239-1.2008.10.1.2
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