AAT1236 Analogic Corporation, AAT1236 Datasheet - Page 16

• Manufacturer Part Number: AAT1236
• Manufacturer: Analogic Corporation

Constant Current Setting
The LED current is controlled by the R
For maximum accuracy, a 1% tolerance resistor is
recommended. Table 2 shows the R
value for AAT1236 for various LED full-scale cur-
rent levels.
16
Resistor Values (1% Resistor Tolerance).
Table 2: Maximum LED Current and R
SDA
SCL
I
Enable/Set
LED
JP6
JP7
30
25
20
15
10
5
(mA)
3
2
1
2
1
Figure 8: A AAT1236-based High Efficiency White LED Driver Schematic.
VIN
R4
4.7k
(optional)
R5
4.7k
(optional)
R
187k
SET
C1
2.2µF
R2
14.7
17.4
22.6
29.4
44.2
93.1
(kΩ Ω )
SET
SET
R3
12.1k
resistor.
resistor
LED1
LED2
LED3
LED4
JP1
0
JP6
0
SET
R1
22.6k
L1: 2.2µH Taiyo Yuden NR4018T2R2M
C1: 0805 10V 2.2µF X7R GRM21BR71A225KA01
C2: 0805 25V 2.2µF X7R GRM21BR71E225KA73L
LED1-24: OSRAM LW M673 or equivalent
LED6
LED7
LED8
LED9
JP2
0
JP7
0
1
2
3
4
5
6
7
8
U1
AAT1236_TDFN3X4
VIN
OV
EN
B1
B2
RSET
IN
GND
High Efficiency White LED Drivers
Maximum LED current per channel versus R
value is shown in Figure 7.
VOUT
AGND
MBR0530T1
SDA
SCL
SW
LIN
A1
A2
A3
SW_Node
Figure 7: LED Current vs. R
2.2µH
35
30
25
20
15
10
5
0
D1
L1
16
15
14
13
12
11
10
9
10
36
for Backlight and Keypad
62
RTN
JP3
0
LED11
LED12
LED13
LED14
JP8
0
88
114
JP4
0
LED16
LED17
LED18
LED19
JP9
0
R
140
SET
(kΩ Ω )
166
JP5
0
LED21
LED22
LED23
LED24
JP10
0
192
SET
1236.2007.01.1.0
218
Values.
25V
C2
2.2µF
244
270
SET