Datasheet

Data Sheet ADP8861
Rev. B | Page 11 of 40
THEORY OF OPERATION
The ADP8861 provides a powerful charge pump driver with
programmable LED control. Up to seven LEDs can be indepen-
dently driven up to 30 mA (typical) each. The seventh LED can
also be driven to 60 mA (typical). All LEDs can be individually
programmed or combined into a group to operate backlight
LEDs. A full suite of safety features, including short-circuit,
overvoltage, and overtemperature protection with input-to-
output isolation, allows for a robust and safe design. The
integrated soft start limits inrush currents at startup, restart
attempts, and gain transitions.
I
2
C
LOGIC
C1
1µF
C2
1µF
GND2
nINT
C
OUT
VOUT
C
IN
VIN
VIN
V
REFS
I
REFS
STNDBY
EN
VIN
VBAT
C1+
SDA
SCL
VDDIO
STANDBY
SWITCH CONTROL
CURRENT SINK CONTROL
C1–
C2+
C2–
nRST
NOISE FILTER
50µs
RESET
D2
D3
D4
D5
D6
D7
D1
ID1
ID2
ID3
ID4 ID5
ID6
ID7
V
IN
GND1
CLK
UVLO
SOFT
START
I
SS
CHARGE
PUMP
LOGIC
GAIN
SELECT
LOGIC
CHARGE
PUMP
(1×, 1.5×, 2×)
08391-011
Figure 25. Detailed Block Diagram