SA8803

sames

4/10

FUNCTIONAL DESCRIPTION

1.

Control Word

The control word written serially into the DATA pin, will contain 9 information bits.

The data structure is illustrated in Figure 2 below.

Because the chip address is 3 bits wide, a single chip controller will be able to

address 8 SA8803 devices. Each SA8803 can drive 24 LED's, which means that

the controller is capable of addressing 192 LED's. The address bits in the control

word are internally compared with the address on the AD0..AD2 address lines to

determine if the SA8803 is being addressed.

Table 1. LED Addresses

L5

L4

L3

L2

L1

LED

0

0

0

0

0

IGNORED

00

0

0

1

1

00

0

1

0

2

etc

11

0

0

0

24

11

0

0

1

IGNORED

11

1

1

1

FIGURE 2: CONTROL WORD STRUCTURE

9-BIT CONTROL WORD

LED BIT ADDRESS INSIDE BANK

DEVICE BIT ADDRESS

STATUS BIT

S=

DR-00595

=

=

=

=

L1

SB

E

SB

A0 ... A2

L1 ... L5

START BIT

END BIT

L2

L3

L4

A1

L5

S

A0

ESB

A2

As can be seen from the structure of the control word, the controller should send 1

start bit, 9 data bits, and 1 stop bit.

When a LED is addressed its state will be set according to the status bit. A logic

one will enable the LED, and a logic zero will disable the LED.