AAT2856
High Current Charge Pump with
Dual LDO for BacklightApplications
Since only one of the scales can be active at any
given time, the 20mA and 30mA scales cannot be
mixed between main and sub. When setting Address
12 to the 30mA scale, only current levels from that
scale can be mixed between main and sub.
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
Data
Maximum Current
1
2
20mA
30mA
Table 6: Address 12 Maximum Current
Settings.
9
10
11
12
13
14
15
16
Backlight Independent Channel Control
(Address 15)
The AAT2856 has a unique independent channel
control mode whereby individual backlight LED
channels can be enabled and disabled to form a
custom arrangement of active channels.
Table 8: Sub-Address 2: BL3-BL6
On/Off Control.
To enable independent channel control mode, write
Data 8 to Address 15. To exit individual mode con-
trol, the AAT2856 state machine can be reset by
strobing ENS low and holding ENS low longer than
Data
BL2
BL1
2
1
2
3
4
5
6
7
8
9
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
the A SCwire's tOFF latch time.
Data
Individual Backlight Control
8
On
Table 7: Address 15, Independent
Backlight Control.
With independent channel control mode enabled,
Addresses 2 and 3 are re-mapped according to
Tables 8 and 9. As indicated by the possible set-
tings listed in the tables, any combination of back-
lighting channels can be enabled and disabled.
10
11
12
13
14
15
16
Table 9: Sub-Address 3: BL1 and BL2
On/Off Control.
Because Addresses 2 and 3 are re-mapped when
independent channel control mode is enabled, the
functions originally assigned to Addresses 2 and 3
are no longer available.
2856.2007.06.1.0
13
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
