MAX6975 Maxim Integrated Products, MAX6975 Datasheet - Page 15

• Manufacturer Part Number: MAX6975
• Description: (MAX6974 / MAX6975) 24-Output PWM LED Drivers
• Manufacturer: Maxim Integrated Products

The global-intensity data is received in an intermediate
register and is applied to the outputs at subframe 0 and
PWM clock 0.
The MAX6974/MAX6975 have one byte of configuration
data with 5 active bit settings as shown in
byte of data containing configuration bit settings is sent
three times. Data is updated immediately into the CAL-
DAC latches. See
settings take effect immediately.
Table 6. Load Configuration Bit Definitions
MSB
LSB
CONFIGURATION BIT
D7
D3
D0
D6
D5
D4
D2
D1
______________________________________________________________________________________
Table
ACRONYM
PWM-ON
10 . The loaded configuration
WDOG
GLB4
CRST
MUX
—
—
—
Global quarter
Reset frame
FUNCTION
Watchdog
individual
and PWM
Multiplex
counters
Enable
enable
enable
PWMs
Table
0
0
0
24-Output PWM LED Drivers
6. One
Not used
Not used
Not used
Enables the reduced global-intensity setting in the MAX6975 when set to
1. When set, the MAX6975 uses eight (or four, if multiplexing) PWM
subframes. GLB4 is set to 0 as power-on default. Setting bit D4 has no
effect in the MAX6974.
Turns all individual PWM outputs on when set to 1. Power-on default is
PWM-ON set to 0 to disable all current output drivers. PWM-ON can be
used to turn all LEDs on or off without affecting the global-intensity or
individual PWM settings.
Setting CRST to 1 synchronously resets internal counters to 0. This action
sets the MAX6974/MAX6975 to subframe 0 of the global-intensity
subframe counter and clock 0 of all individual PWM counters. The CRST
bit is a nonlatching control function that resets to 0 after the counters are
set to 0.
Setting WDOG to 1 enables the watchdog timer operation. Power-on
default is 0.
Setting MUX to 1 turns multiplex mode on. Power-on default is 0.
The MAX6974/MAX6975 feature a fully synchronous
and fully buffered serial interface that allows cascading
of multiple devices. The serial interface consists of
inputs (CLKI, DIN, and LOADI) and outputs (CLKO,
DOUT, and LOADO). The MAX6974/MAX6975 can
pass different data to each cascaded device without
any additional inputs to identify the position of the
devices in the cascaded chain.
for Message Boards
DESCRIPTION
Serial Interface
15