Datasheet

20 Maxim Integrated
Integrated, 4-Channel, High-Brightness LED
Driver with High-Voltage DC-DC Controller
MAX16814
with C
COMP
and R
COMP
. Figure 5 shows the SEPIC
configuration and Figure 6 shows the coupled-inductor
boost-buck configuration.
Analog Dimming Using External
Control Voltage
Connect a resistor R
SETI2
to the SETI input as shown in
Figure 7 for controlling the LED string current using an
external control voltage. The MAX16814 applies a fixed
1.23V bandgap reference voltage at SETI and measures
the current through SETI. This measured current mul-
tiplied by a factor of 1220 is the current through each
one of the four constant current-sink channels. Adjust
the current through SETI to get analog dimming func-
tionality by connecting the external control voltage to
SETI through the resistor R
SETI2
. The resulting change
in the LED current with the control voltage is linear and
inversely proportional. The LED current control range
remains between 20mA to 150mA.
Use the following equation to calculate the LED current
set by the control voltage applied:
( )
C
OUT
SETI SETI2
1.23 V
1500
I 1220
RR
−
=+×
Figure 5. SEPIC Configuration
OUT1
OVPCSNDRVIN
EN
DRV
V
CC
C
S
D1
C2
UP TO 40V
R
CS
R
SCOMP
MAX16814
OUT2
OUT3
OUT4
SETI
FLT
V
CC
R3
R
SETI
R4
R
T
RSDT
RT
PGND LEDGNDSGND
L1
V
IN
4.75V TO 40V
C1
N
R1
L2
R2
C3
R5
C4
DIM
COMP
R
COMP
C
COMP