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The MAX6968 serial-interfaced LED driver provides
eight open-drain, constant-current sinking LED driver
outputs rated at 5.5V. The MAX6968 operates from a 3V
to 5.5V supply. The MAX6968 supply and the LEDs'
supply or supplies may power up in any order. The
constant-current outputs are programmed together to
up to 55mA using a single external resistor. The
MAX6968 operates with a 25Mb, industry-standard, 4-
wire serial interface.
The MAX6968 uses the industry-standard shift-register-plus-
latch-type serial interface. The driver accepts data
shifted into an 8-bit shift register using data input DIN
and clock input CLK. Input data appears at the output
DOUT eight clock cycles later to allow cascading of
multiple MAX6968s. The latch-enable input LE loads
the 8 bits of shift register data into an 8-bit output latch
to set which LEDs are on and which are off. The output-enable
input OE-bar gates all eight outputs on and off, and
is fast enough to be used as a PWM input for LED
intensity control.
For applications requiring LED fault detection, refer to
the MAX6977 data sheet that automatically detects
open-circuit LEDs.
For safety-related applications requiring a watchdog
timer, refer to the MAX6978 data sheet that includes a
fail-safe feature that blanks the display if the serial interface
becomes inactive for more than 1s.
The MAX6968 is one of a family of 12 shift-register-plus-latch-
type LED drivers. The family includes 8-port and
16-port types, with 5.5V- or 36V-rated LED outputs, with
and without open-circuit LED detection and watchdog.
All versions operate from a 3V to 5.5V supply, and are
specified over the -40°C to +125°C temperature range.
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