MAX16838B Datasheet, PDF (18/21 Pages) Maxim Integrated Products – Integrated, 2-Channel, High-Brightness LED Driver with High-Voltage Boost and SEPIC Controller

MAX16838B
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
3) There are two loops in the power circuit that carry
high-frequency switching currents. One loop is when
the MOSFET is on—from the input filter capacitor
positive terminal, through the inductor, the internal
MOSFET, and the current-sense resistor, to the input
capacitor negative terminal. The other loop is when
the MOSFET is off—from the input capacitor positive
terminal, through the inductor, the rectifier diode,
output filter capacitor, to the input capacitor nega-
tive terminal. Analyze these two loops and make the
loop areas as small as possible. Wherever possible,
have a return path on the power-ground plane for the
switching currents on the top-layer copper traces, or
through power components. This reduces the loop
area considerably and provides a low-inductance path
for the switching currents. Reducing the loop area also
reduces radiation during switching.
4) Connect the power-ground plane for the constant-
current LED driver part of the circuit to LEDGND as
close as possible to the device. Connect SGND to
PGND at the same point.
VIN
C₁
CIN
R1EN
R2EN
CVCC
RDRV
CDRV
RCOMP
CCOMP
D₁
VDD
BST
MAX15054
HDRV
GND
HI
LX
CBST
Q1
L
D2
D3
COUT
R1OV
IN
EN
CFB
VCC
DRV
GATE
NDRV
DRAIN
OV
OUT1
OUT2
MAX16838B
ISET
RISET
R2OV
DIM
COMP
SGND
PGND
FLT
CS
RT
LEDGND
RRT RCS
LED
STRINGS
Figure 5. Boost-Buck Configuration
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