MAX16823_09 Datasheet, PDF (8/12 Pages) Maxim Integrated Products – High-Voltage, 3-Channel Linear High-Brightness LED Driver with Open LED Detection

High-Voltage, 3-Channel Linear High-Brightness
LED Driver with Open LED Detection
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:
V_IN(MIN) > V_BE(MAX) + V_FT(MAX) + V_{CS_} + V_DO(MAX)
For minimized dropout, the LEDs can be placed in the
collector.
t_ON
DIM
LEDGOOD
t_OFF
LEDGOOD GOES
LOW WHEN t_OFF > t_DELAY
Figure 1. LEDGOOD Timing Delay
STOP
D1
TAIL
D4
R1
C1
R2
D2
DIS
IN
OUT
R3
D3
TH
GND
100kΩ
TRG
C2
ICM7555
IN
OUT3
OUT2
OUT1
REG
0.1μF
LEDs
DIM1 ^MAX16823
CS1
DIM2
R_CS1
CS2
DIM3
R_CS2
CS3
GND
R_CS3
Figure 2. PWM Dimming Operation with ICM7555
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