Datasheet

ADM8845
Rev. C | Page 15 of 20
DRIVING FLASH LEDs
The ADM8845 can be operated with any two FBx pins used in
parallel to double the combined LED current supplied by the
ADM8845. For example, if three flash LEDs need to be driven
with 60 mA/LED, the ADM8845 can be configured as in
Figure 31 (see also Figure 21).
V
OUT
FB1
FB2
FB3
FB4
FB5
FB6
V
CC
2.6V–5.5V
CTRL1
CTRL2
GND
ADM8845
R
SET
4.27kΩ
04867-0-031
60mA
60mA
60mA
Figure 31. Driving Three Flash LEDs
DRIVING CAMERA LIGHT, MAIN, AND SUB LEDs
The ADM8845 can be configured to power a camera light that
is composed of four white LEDs in parallel, along with the main
and sub display bundled into one package. FB1 to FB4 now
power the camera light, and FB5 and FB6 power the main
display. The sub display LED is powered from the ADM8845 by
using an external current mirror to control the current flowing
through the sub white LED (see Figure 32
). All white LEDs have
15 mA/LED. Total load on the ADM8845 charge pump is
therefore 105 mA, and the maximum load on the ADM8845
charge pump is 180 mA (see Figure 21).
��
CURRENT
CONTROL 1
CURRENT
CONTROL 2
CURRENT
CONTROL 3
CURRENT
CONTROL 4
CURRENT
CONTROL 5
CURRENT
CONTROL 6
CONTROL
LOGIC
V
REF
CHARGE PUMP
1×/1.5×/2× MODE
OSC
LED
CURRENT
CONTROL
CIRCUIT
FB1
CURRENT CONTROLLED SINKS
FB2
FB3
FB4
FB5
FB6
V
OUT
C4
4.7µF
VCC
C1
1µF
CTRL1
CTRL2
C2
1µF
R
SET
9.44kΩ
I
SET
GND
C3
2.2µF
ADM8845
04867-0-032
15mA/LED
15mA/LED
15mA/LED
CURRENT
CONTROL7
R
CAMERA MAIN SUB
Figure 32. Driving Camera Light, Two Main LEDs, and One Sub LED