ADP8860 Analog Devices, ADP8860 Datasheet - Page 18

• Manufacturer Part Number: ADP8860
• Description: Charge Pump, 7-Channel Smart LED Driver with I2C Interface
• Manufacturer: Analog Devices

Specifications of ADP8860

• Vin Range: 2.4V to 5.5V
• Vout (v): 4.3 to 5.5
• Synchronous: No
• Package: 20-Lead WLCSP
• Led Configuration: Parallel
• Topology: Capacitive
• I2c Support: Yes
• Max Iout (ma): 60mA
• Brightness Control: I2C
• Peak Efficiency (%): 89%
• Switching Frequency: 1MHz

ADP8860
The backlight turns on when BL_EN = 1. The backlight turns
off when BL_EN = 0.
While the backlight is on (BL_EN = 1), the user can change to
the dim setting by programming DIM_EN = 1 in Register 0x01.
If DIM_EN = 0, the backlight reverts to its maximum setting.
The maximum and dim settings can be set between 0 mA and
30 mA; therefore, it is possible to program a dim setting that is
greater than a maximum setting. For normal expected opera-
tion, ensure that the dim setting is programmed to be less than
the maximum setting.
AUTOMATIC DIM AND TURN OFF TIMERS
The user can program the backlight to dim automatically by
using the DIMT timer in Register 0x07. The dim timer has 127
settings ranging from 1 sec to 127 sec. Program the dim timer
(DIMT) before turning on the backlight. If BL_EN = 1, the
backlight turns on to its maximum setting and the dim timer
starts counting. When the dim timer expires, the internal state
machine sets DIM_EN = 1, and the backlight enters its dim
setting.
MAX
BACKLIGHT
DIM
BACKLIGHT
MAX
CURRENT
CURRENT
Figure 33. Backlight Turn On/Dim/Turn Off
BL_EN = 1
BL_EN = 1
Figure 32. Backlight Turn On/Off
DIM_EN = 1
DIM_EN = 0
BL_EN = 0
BL_EN = 0
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If the user clears the DIM_EN bit, the backlight reverts to its
maximum setting and the dim timer begins counting again.
When the dim timer expires, the internal state machine again
sets DIM_EN = 1, and the backlight enters its dim setting. The
backlight can be turned off at any point during the dim timer
countdown by clearing BL_EN.
The user can also program the backlight to turn off automati-
cally by using the OFFT timer in Register 0x06. The off timer
has 127 settings ranging from 1 sec to 127 sec. Program the off
timer (OFFT) before turning on the backlight. If BL_EN = 1,
the backlight turns on to its maximum setting and the off timer
starts counting. When the off timer expires, the internal state
machine clears the BL_EN bit, and the backlight turns off.
The backlight can be turned off at any point during the off
timer countdown by clearing BL_EN.
The dim timer and off timer can be used together for sequential
maximum-to-dim-to-off functionality. With both the dim and
off timers programmed, if BL_EN is asserted, the backlight
turns on to its maximum setting, and when the dim timer
expires, the backlight changes to its dim setting. When the off
timer expires, the backlight turns off.
MAX
BACKLIGHT
DIM
CURRENT
BACKLIGHT
MAX
SET BY USER
SET BY INTERNAL STATEMACHINE
CURRENT
SET BY USER
SET BY INTERNAL STATE MACHINE
BL_EN = 1
DIM TIMER
RUNNING
DIM_EN = 1
Figure 34. Dim Timer
BL_EN = 1 BL_EN = 0
Figure 35. Off Timer
OFF TIMER
RUNNING
DIM_EN = 0 DIM_EN = 1
DIM TIMER
RUNNING
BL_EN = 0