MAX16839 Datasheet, PDF (8/11 Pages) Maxim Integrated Products – High-Voltage, Linear High-Brightness LED Driver with Open-LED Fault Detect

High-Voltage, Linear High-Brightness LED
Driver with Open-LED Fault Detect
The MAX16839 detects an open-LED event when VCS
drops below 30mV for 25µs. When the fault condition
is detected, the LED driver is turned off, and a 2.8mA
current source charges the capacitor between FLTS
and ground, up to 15V or to VIN if VIN is less than 15V.
During subsequent power cycles, if the voltage on FLTS
is greater than 1.65V due to the charge retained in the
FLTS capacitor, the LED driver is turned off. This pro-
vides an open-LED fault-protection feature that can be
disabled by connecting FLTS to ground. In a multistring
application (Figure 2), where all FLTS pins are connected
together, a fault detected on one channel causes other
channels to turn off as well. The retention capability on
the FLTS is dependent on the leakage current and the
value of the capacitor used. If the retention capability is
high, the fault condition could be retained or memorized
for a long period after the supply is turned off.
Thermal Protection
The MAX16839 enters thermal-shutdown mode in the
event of overheating. When the junction temperature
exceeds TJ = +160NC, the internal thermal-protection
circuit turns off the series pass element. The MAX16839
recovers from thermal-shutdown mode when the junc-
tion temperature drops to TJ = +145NC. FLTS does not
assert during an overheating event.
VIN
12V
ILED
50mA
LEDGOOD (INTERNAL)
12V FLTS
12V
t
UVLO
t
50mA
t
t
4Fs
VIN = 5V TO 40V
VIN
t
ILED
t
2.5Fs
LEDS
C_IN =
0.01FF
IN
ILED
SINK
DIM
MAX16839
CS
FLTS
GND
RCS
CONNECT TO 5V
SUPPLY OR LEAVE
UNCONNECTED
DIM SIGNAL
FLTS SIGNAL
CFLTS =
0.1FF
CIN =
0.01FF
LED_S
IN
ILED
DIM
SINK
MAX16839
FLTS
CS
GND
R_CS
Figure 2. Multistring Application
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