MAX16823
High-Voltage, 3-Channel Linear High-Brightness
LED Driver with Open LED Detection
8 _______________________________________________________________________________________
ICM7555. When V
STOP
is present, DIM is pulled up to
V
STOP
. The PWM dimming operation is disabled and
the LEDs light up to full brightness. See the ICM7555
data sheet for formulas to calculate the dimming fre-
quency and the duty cycle.
Outputs Latch-Off
Figure 3 shows a circuit with DIM1, DIM2, DIM3, and
LEDGOOD connected through a resistor to V
REG
. This
circuit is useful for applications that require all outputs
to latch off when one of the LEDs opens. The
MAX16823 resumes current regulation again through
power cycling, once the fault condition is removed.
Other Applications
The application circuit in Figure 4 implements a two-
level brightness current for TAIL/STOP lights. In TAIL
operation, Q1 is off and R
CS1
sets the output current. In
STOP operation, Q1 turns on and the output current is
set by a parallel combination of R
CS1
and R2.
Figure 5 shows an application circuit with the
MAX16823 using a single BJT to provide high output
current. For proper operation:
For minimized dropout, the LEDs can be placed in the
collector.
