PRODUCT DATASHEET
AAT2861
TM
ChargePump
Backlight/Flash LED Driver and Multiple LDO Lighting Management Unit
Torch/movie mode is automatically entered when the
flash current setting is programmed to 120mA (60mA for
channel for the AAT2861-2) or lower with Data = 13, 14,
or 15. At these current levels the safety timer is auto-
matically disabled and the flash channels will remain on
as long as the FL_EN pin remains active. Extended dura-
tion flash use can be achieved for higher current settings
by writing Data 4 to Address 11 to disable the safety
timer. Though the AAT2861 includes an internal thermal
limit circuit, be careful to limit the current setting (Address
10) to a value that will not generate excessive heat which
may damage the flash LEDs or external circuitry.
LED Channel Disable Control
(Address 12 and 13)
Addresses 12 and 13 allow for additional programming
flexibility by allowing each LED channel to be indepen-
dently disabled. Normally, the backlight channels are
controlled by MAIN_ON and SUB_ON controls in Address
0, while the FL_EN pin turns on the flash channels.
Writing to Addresses 12 and 13 can override these con-
trols to allow for any combination of LEDs to be turned
on. The default state is for all LED channels to be
“Conditionally ON” to allow the normal enable control.
In the following example we see how to turn on BL1,
BL2, BL6, and BL7 in the AAT2861-1 (4M+3S+1FL). First
write Address 12, Data=13 and Address 13, Data=10 to
disable BL3, BL4, BL5, FL1. Then program the desired
current setting using Addresses 2 through 5. Finally,
write Address 0, Data=4.
Data
Flash Time (sec)
1*
2
2*
1
3
0.5
4
Always ON
(NOTE: ”Conditionally ON” state allows the LED channel
to be turned ON but does not turn the channel ON. For
BL1 to be enabled Data=2, 4, 6, 8… must be written to
Address 0, and Data=1, 3, 5, 7… must be written to
Address 12.)
Table 10: Flash Safety Timer (Address 11).
Data
BL4
BL3
BL2
BL1
1*
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Conditionally ON*
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON*
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON*
Conditionally ON
OFF
Conditionally ON*
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
Conditionally ON
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
Conditionally ON
Conditionally ON
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Conditionally ON
Conditionally ON
OFF
OFF
OFF
OFF
OFF
Table 11: LED Channel Individual Disable Control, BL1-BL4 (Address 12).
*Denotes default (power-on-reset) value.
w w w . a n a l o g i c t e c h . c o m
2861.2009.02.1.2
19
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
