Data Segment

The bit length of the data segment received by the

MAX6972/MAX6973 is dependent on the command

specified in the header.

The load CALDAC command has two unique data

bytes, while load global-intensity PDM and load

configuration each have one byte of data repeated

once. The CALDAC data within the command load

CALDAC is sent with Z CALDAC data first followed by

Y CALDAC data, as shown in Table 8.

The data segment of the load individual PWM command

has a variable length depending on specific device and

configuration settings. The data is always organized

as Z driver data first in the order of Z7 first to Z0 last

(MSB first), followed by the Y driver data in the same

order of Y7 to Y0 (MSB first).

Tail Segment

The MAX6972/MAX6973 allow for an optional string of

data bits to be transmitted following all device data

bits, which is referred to as the tail segment. The data

bits of the tail segment are clocked back to the host,

following the header, from the last device in a cascaded

chain. The number of bits in the tail segment is optional.

The tail carries no device-specific data on DIN, but

provides feedback confirmation to the host that all data

bits were extracted by all devices in the cascade chain.

16-Output PWM LED Drivers

for Message Boards

18

______________________________________________________________________________________

HEADER

DATA 1

DATA 2

DATA 3

…

DATA N

HDR[23:0]

Z[7:0] Y[7:0]

Z[7:0] Y[7:0]

Z[7:0] Y[7:0]

…

Z[7:0] Y[7:0]

Table 8. Serial Format for Load CALDAC

HEADER

DATA 1

DATA 2

DATA 3

…

DATA N

HDR[23:0]

D[7:0] D[7:0]

D[7:0] D[7:0]

D[7:0] D[7:0]

…

D[7:0] D[7:0]

Table 9. Serial Format for Load Global-Intensity PDM

HEADER

DATA 1

DATA 2

DATA 3

…

DATA N

HDR[23:0]

D[7:0] D[7:0]

D[7:0] D[7:0]

D[7:0] D[7:0]

…

D[7:0] D[7:0]

Table 10. Serial Format for Load Configuration

HEADER

DATA 1

DATA 2

DATA 3

…

DATA N

HDR[23:0]

Z7, Z6, …Y0

Z7, Z6, …Y0

Z7, Z6, …Y0

…

Zn…Yn

Table 11. Serial Format for Load Individual PWM (Nonmultiplexed)

HEADER

DATA 1

DATA 2

DATA 3

…

DATA N

HDR[23:0]

Z7, Z7', Z6, Z6', …Y0'

Z7, Z7', Z6, Z6', …Y0'

Z7, Z7', Z6, Z6', …Y0'

…

Z7, Z7', Z6, Z6', …Y0'

Table 12. Serial Format for Load Individual PWM (Multiplexed)

Z[7:0]

8-bit data loaded into port Z CALDAC

Y[7:0]

8-bit data loaded into port Y CALDAC

N

Number of cascaded devices

D[7:0]

Send the same data repeated (16 total bits) for the 8-bit data for global-intensity PDM

Send the 8-bit data for the global-intensity PDM twice (16 total bits)

D[7:0]

Send the same data repeated (16 total bits) for the 8-bit data for configuration

Send the 8-bit configuration data two times (16 total bits)

Z_…Y_

12-bit (MAX6972) or 14-bit (MAX6973) data each

Z_

12-bit (MAX6972) or 14-bit (MAX6973) PWM data for each output Z_ during multiplex phase MUX0, MSB first

Z_'

12-bit (MAX6972) or 14-bit (MAX6973) PWM data for each output Z_ during multiplex phase MUX1, MSB first

Y_

12-bit (MAX6972) or 14-bit (MAX6973) PWM data for each output Y_ during multiplex phase MUX0, MSB first

Y_'

12-bit (MAX6972) or 14-bit (MAX6973) PWM data for each output Y_ during multiplex phase MUX1, MSB first