MAX16814_15 Datasheet, PDF (20/25 Pages) Maxim Integrated Products – Integrated, 4-Channel, High-Brightness LED Driver with High-Voltage DC-DC Controller

MAX16814
Integrated, 4-Channel, High-Brightness LED
Driver with High-Voltage DC-DC Controller
with CCOMP and RCOMP. 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 RSETI2 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
multiplied 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
functionality by connecting the external control voltage
to SETI through the resistor RSETI2. 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:
I_OUT
= ¹⁵⁰⁰
R _SETI
+
(1.23 − V_C)
R _SETI2
× 1220
V_IN
4.75V TO 40V
C1
L1
C_S
D1
N
L2
C2
R1
R_SCOMP
R_CS
R2
UP TO 40V
C3
R5
C4
R_COMP
C_COMP
IN NDRV
CS
OVP
EN
V_CC
DRV
DIM
COMP
MAX16814
OUT1
OUT2
OUT3
OUT4
R_SETI
SETI
FLT
RSDT
V_CC
R3
RT
R4
SGND PGND LEDGND
R_T
Figure 5. SEPIC Configuration
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