M5481

4/8

Figure 2. Input Data Format

At the low state of the clock a RESET signal is

generated which clears all the shift registers for

the next set of data. The shift registers are static

master slave configurations. There is no clear for

the master portion of the first shift register, thus al-

lowing continuous operation.

There must be a complete set of 36 clocks or the

shift registers will not clear.

When power is first applied to the chip an internal

power ON reset signal is generated which resets

all registers and all latches. The START bit and the

first clock reset the chip to its normal operation.

Data, Clock and DATA ENABLE.

A maximum clock frequency of 0.5MHz is as-

sumed.

M5481. Because it uses only 14 of the possible 35

outputs, 21 of the bits are “Don’t Cares”.

For applications where a lesser number of outputs

are used it is possible to either increase the cur-

rent per output or operate the part at higher than

1V Vout.

The following equation can be used for calcula-

tions.

x(80°C/W)+Tamb

where:

Tj=junction temperature (150°Cmax)

Vout= voltage at the LED driver outputs

ILED= LED current

80°C/W=thermal coefficient of the package

Tamb=ambiant temperature

Figure 3.

Figure 4. Serial Bus/Outputs Correspondance

36

BIT 34

BIT 35

CLOCK

DATA

LOAD

(INTERNAL)

RESET

(INTERNAL)

START

BIT 1

1

CLOCK

DATA

300ns (min.)

100ns (min.)

DATA ENABLE

5450

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

START

5481

XXXX

13

XXXXX

12

11

10

9

XXX

START

5450

17

16

15

14

13

12

11

10

987

654321

START

5481

X

8765

XXXX

4

3

2

1

XXXX

START