AAT2846_08 Datasheet, PDF (11/22 Pages) Advanced Analogic Technologies – High Current Charge Pump with Dual LDO for Backlight and Flash Applications

PRODUCT DATASHEET
AAT2846
ChargePump^TM High Current Charge Pump with Dual LDO for Backlight and Flash Applications
AS²Cwire Serial Interface Addressing
Address
0
1
2
3
4
5
12
15
Sub-2
Sub-3
ENS Rising
Edges
17
18
19
20
21
22
29
32
19
20
Function
Backlight Current BL1-BL6
Main Backlight Current BL1-BL5
Sub Backlight Current BL6
Low Current Backlight
Flash Current FL1, FL2
Independent Flash On/Off Control
Maximum Backlight Current
(Main and Sub)
Backlight Independent Control
BL3-BL6 On/Off Control
BL1/BL2 On/Off Control
Table 1: AS²Cwire Serial Interface Addressing.
Backlight Current Control (Address 0-3)
Use Addresses 0-3 to program all six backlight LED
channels. All six backlight channels are programmed to
the same current level by writing Address 0 followed by
any Data between 1 and 16. To program only the main
channels BL1 through BL5, use Address 1. Similarly, use
Address 2 to independently program subchannel BL6
only.
Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
30mA Max (mA)
30.0
27.9
26.1
24.2
21.0
19.2
17.3
15.0
12.7
10.9
8.1
6.2
4.4
3.5
2.6
0
20mA Max (mA)
20.0
19.0
17.8
16.5
14.3
13.0
11.8
10.2
8.5
7.3
5.4
4.1
2.9
2.2
1.6
0
Table 2: Data Code for Backlight Current Level,
Address 0-2.
35.0
30.0
25.0
20.0
15.0
20mA (Full Scale)
10.0
30mA (Full Scale)
5.0
0.0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Data Code
Figure 2: Data Code for Address 0-2
vs. Backlight Current Level.
The AAT2846 incorporates additional circuitry that opti-
mizes performance for exceptionally low backlight cur-
rent settings. A separate address is used to activate this
circuitry. To program the low current settings with
improved performance and efficiency, write to Address
3. Unlike Addresses 0-3, which have current level set-
tings according to Table 2 and Figure 2, Address 3 pos-
sesses a separate set of current levels described by the
Low Current Backlight settings found in Table 3.
Data
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Main Current
On
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Sub Current
On
No
No
No
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Current
(µA)
0
0
0
0
95
500
950
1900
95
500
950
1900
95
500
950
1900
Table 3: Data Code for Low-Level Backlight
Current, Address 3, FS = 20mA range.
2846.2008.03.1.1
www.analogictech.com
11