AAT2833/34
240mA Total Display Solution
for Portable Devices
120
100
80
60
40
20
0
Backlight Independent Channel Control
(Address 15)
The AAT2833/34 can also individually control each
backlight channel. This mode allows the user to turn
on some or all of the channels in any desired com-
bination. This control is achieved by changing the
2
functionality of the AS Cwire registers. To enable
individual LED control mode, a user would write
Data 8 to Address 15. All channels that are enabled
must carry the same current, which is set using the
new functionality of Address 1 (see Table 2b).
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
Data Code
Figure 1: Addresses 0-2 Backlight Current Level.
Data
Individual BL Control
8
On
Low Backlight Current (Address 3)
Table 4: Address 15, Backlight Independent
Channel Control
In addition to the current levels set by Addresses 0,
1, and 2 (shown in Table 2a and Figure 1), there is
also a low backlight current level that can be set. To
set the low backlight current level, the user would
write data to Address 3, as shown in Table 3.
Data
1
2
3
4
5
6
7
8
BL6
BL5
BL4
BL3
Off
Off
Off
Off
Off
Off
Off
Off
On
On
On
On
On
On
On
On
Off
Off
Off
Off
On
On
On
On
Off
Off
Off
Off
On
On
On
On
Off
Off
On
On
Off
Off
On
On
Off
Off
On
On
Off
Off
On
On
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
Off
On
For example, to toggle between 1.7% and 25% of the
maximum backlight current on all LEDs, write Data =
14 to Address 3 and Data 4 to Address 0. To set BL1-
BL4 to 25% and BL5-BL6 to 0.2%, write Data = 5 to
Address 3, and Data = 4 to Address 2.
BL1-BL4
BL5-BL6
BL %
Data
Current On Current On of BSET
9
1
2
No
No
No
No
0
0
10
11
12
13
14
15
16
3
No
No
0
4
No
No
0
5
6
7
8
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
0.2
1.7
3.5
7.0
0.2
1.7
3.5
7.0
0.2
1.7
3.5
7.0
Table 5: Address 2 with Independent
Channel Control Enabled, BL3-BL6
On/Off Control.
9
10
11
12
13
14
15
16
Table 3: Address 3 with Independent Channel
Control Disabled, Low-Backlight Current
Levels (RBSET = 280kΩ).
2833.2007.09.1.0
11
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
