AAT2856 AAT, AAT2856 Datasheet - Page 12

• Manufacturer Part Number: AAT2856
• Description: High Current Charge Pump
• Manufacturer: AAT

The AAT2856 incorporates additional circuitry that
optimizes performance for exceptionally low back-
light current 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 0-2, which
have current level settings according to Table 2 and
Figure 2, Address 3 possesses a separate set of
current levels described by the Low Current
Backlight settings found in Table 3.
12
Figure 2: Data Code for Address 0-3 vs.
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
1
20mA (Full Scale)
Backlight Current Level.
2
3
4
5
Data Reg 2
Data Reg 1
Address
6
EN/SET
Data Code
7
8
9
30mA (Full Scale)
10 11 12 13 14 15 16
Figure 1: AS
1
2
Address
T
2
LO
Cwire Serial Interface Timing.
17
0
T
HI
18
T
Dual LDO for BacklightApplications
LAT
Maximum Backlight Current
(Address 12)
There are two separate current level scales that apply
to Addresses 0-2: 20mA and 30mA. According to the
Maximum Backlight Current setting at Address 12,
only one of the two scales can be active at any given
time and never both. By default, the 20mA scale is
active on startup. To change to the 30mA scale, or go
back to the 20mA scale, write to Address 12.
High Current Charge Pump with
0
0
Data
10
12
13
14
15
16
11
1
2
3
4
5
6
7
8
9
Table 3: Low-Level Backlight Current,
1
Address 3, FS = 20mA range.
2 . . .
Current On Current On
Data
Main
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
n <= 16
1
T
LAT
n
Sub
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
AAT2856
2856.2007.06.1.0
Current
1900
1900
1900
(µA)
500
950
500
950
500
950
95
95
95
0
0
0
0