Datasheet

AD9838
Rev. A | Page 23 of 32
NO
YES
DATA WRITE
NO
YES
YES
NO
YES
NONO
YES
YES
WRITE A FULL 28-BIT WORD
TO A FREQUENCY REGISTER?
(CONTROL REGISTER WRITE)
B28 (D13) = 1
WRITE TWO CONSECUTIVE
16-BIT WORDS
(SEE TABLE 12 FOR EXAMPLE)
WRITE ANOTHER FULL
28-BIT WORD TO A
FREQUENCY REGISTER?
WRITE 14 MSBs OR LSBs
TO A FREQUENCY REGISTER?
(CONTROL REGISTER WRITE)
B28 (D13) = 0
HLB (D12) = 0/1
WRITE A 16-BIT WORD
(SEE TABLE 13 AND TABLE 14
FOR EXAMPLES)
WRITE 14 MSBs OR LSBs
TO A
FREQUENCY REGISTER?
WRITE TO PHASE
REGISTER?
D15, D14 = 11
D13 = 0/1 (CHOOSE THE
PHASE REGISTER)
D12 = X
D11 ... D0 = PHASE DATA
(16-BIT WRITE)
WRITE TO ANOTHER
PHASE REGISTER?
09077-030
Figure 26. Flowchart for Data Writes
SELECT DATA SOURCES
YES
NO
FSELECT AND PSELECT
PINS BEING USED?
(CONTROL REGISTER WRITE)
PIN/SW = 0
SET FSEL BIT
SET PSEL BIT
SET FSELECT AND
PSELECT PINS
(CONTROL REGISTER WRITE)
PIN/SW = 1
09077-031
Figure 27. Flowchart for Selecting Data Sources