Data Sheet

AD9943/AD9944

SERIAL INTERFACE

Figure 10. Serial Write Operation

Figure 11. Continuous Serial Write Operation to All Registers

SDATA

SCK

SL

TEST BIT

A2

0

A0

A1

D0

D1

D2

D3

D4

D5

D6

D7

D8

D9

D10

NOTES

1. SDATA BITS ARE INTERNALLY LATCHED ON THE RISING EDGES OF SCK.

2. SYSTEM UPDATE OF LOADED REGISTERS OCCURS ON SL RISING EDGE.

3. ALL 12 DATA BITS D0–D11 MUST BE WRITTEN. IF THE REGISTER CONTAINS FEWER THAN 12 BITS, ZEROS SHOULD BE USED

FOR THE UNDEFINED BITS.

4. TEST BIT IS FOR INTERNAL USE ONLY AND MUST BE SET LOW.

D11

SDATA

A0

A1

A2

D0

D1

D2

D3

D4

D5

D10

D11

SCK

SL

0

NOTES

1. MULTIPLE SEQUENTIAL REGISTERS MAY BE LOADED CONTINUOUSLY.

2. THE FIRST (LOWEST ADDRESS) REGISTER ADDRESS IS WRITTEN, FOLLOWED BY MULTIPLE 12-BIT DATA-WORDS.

3. THE ADDRESS AUTOMATICALLY INCREMENTS WITH EACH 12-BIT DATA-WORD. (ALL 12 BITS MUST BE WRITTEN.)

4. SL IS HELD LOW UNTIL THE LAST DESIRED REGISTER HAS BEEN LOADED.

5. NEW DATA IS UPDATED AT THE NEXT SL RISING EDGE.

D0

D1

D10

D11

D0

...

...

...

DATA FOR STARTING

REGISTER ADDRESS

DATA FOR NEXT

REGISTER ADDRESS

D2

D1

...

...

1

16

2

3

4

5

6

7

8

9

10

15

18

17

28

27

30

29

31

TEST

BIT

Rev. C | Page 13 of 20