Datasheet
Data Sheet AD9517-1
Rev. E | Page 45 of 80
Duty Cycle and Duty-Cycle Correction (Divider 2 and
Divider 3)
The same duty cycle and DCC considerations apply to Divider 2
and Divider 3 as to Divider 0 and Divider 1 (see the Duty Cycle
and Duty-Cycle Correction (0, 1) section); however, with these
channel dividers, the number of possible configurations is even
more complex.
Duty-cycle correction on Divider 2 and Divider 3 requires the
following channel divider conditions:
• An even D
X.Y
must be set as M
X.Y
= N
X.Y
(low cycles = high
cycles).
• An odd D
X.Y
must be set as M
X.Y
= N
X.Y
+ 1 (the number of
low cycles must be one greater than the number of high
cycles).
• If only one divider is bypassed, it must be the second
divider, X.2.
• If only one divider has an even divide-by, it must be the
second divider, X.2.
The possibilities for the duty cycle of the output clock from
Divider 2 and Divider 3 are shown in Table 40 through
Table 44.
Table 40. Divider 2 and Divider 3 Duty Cycle; VCO Divider
Used; Duty Cycle Correction Off (DCCOFF = 1)
VCO
Divider
D
X.1
D
X.2
Output
Duty Cycle
N
X.1
+ M
X.1
+ 2 N
X.2
+ M
X.2
+ 2
Even 1 1 50%
Odd = 3 1 1 33.3%
Odd = 5 1 1 40%
Even Even, odd 1
(N
X.1
+ 1)/
(N
X.1
+ M
X.1
+ 2)
Odd Even, odd 1
(N
X.1
+ 1)/
(N
X.1
+ M
X.1
+ 2)
Even Even, odd Even, odd
(N
X.2
+ 1)/
(N
X.2
+ M
X.2
+ 2)
Odd Even, odd Even, odd
(N
X.2
+ 1)/
(N
X.2
+ M
X.2
+ 2)
Table 41. Divider 2 and Divider 3 Duty Cycle; VCO Divider
Not Used; Duty Cycle Correction Off (DCCOFF = 1)
Input Clock
Duty Cycle
D
X.1
D
X.2
Output
Duty Cycle
N
X.1
+ M
X.1
+ 2 N
X.2
+ M
X.2
+ 2
50% 1 1 50%
X% 1 1 X%
50%
Even, odd
1
(N
X.1
+ 1)/
(N
X.1
+ M
X.1
+ 2)
X% Even, odd 1
(N
X.1
+ 1)/
(N
X.1
+ M
X.1
+ 2)
50% Even, odd Even, odd
(N
X.2
+ 1)/
(N
X.2
+ M
X.2
+ 2)
X%
Even, odd
Even, odd
(N
X.2
+ 1)/
(N
X.2
+ M
X.2
+ 2)
Table 42. Divider 2 and Divider 3 Duty Cycle; VCO Divider
Used; Duty Cycle Correction Is On (DCCOFF = 0); VCO
Divider Input Duty Cycle = 50%
VCO
Divider
D
X.1
D
X.2
Output
Duty Cycle N
X.1
+ M
X.1
+ 2 N
X.2
+ M
X.2
+ 2
Even 1 1 50%
Odd 1 1 50%
Even Even (N
X.1
= M
X.1
) 1 50%
Odd
Even (N
X.1
= M
X.1
)
1
50%
Even Odd (M
X.1
= N
X.1
+ 1) 1 50%
Odd Odd (M
X.1
= N
X.1
+ 1) 1 50%
Even Even (N
X.1
= M
X.1
) Even (N
X.2
= M
X.2
) 50%
Odd Even (N
X.1
= M
X.1
) Even (N
X.2
= M
X.2
) 50%
Even Odd (M
X.1
= N
X.1
+ 1) Even (N
X.2
= M
X.2
) 50%
Odd
Odd (M
X.1
= N
X.1
+ 1)
Even (N
X.2
= M
X.2
)
50%
Even Odd (M
X.1
= N
X.1
+ 1) Odd (M
X.2
= N
X.2
+ 1) 50%
Odd Odd (M
X.1
= N
X.1
+ 1) Odd (M
X.2
= N
X.2
+ 1) 50%
Table 43. Divider 2 and Divider 3 Duty Cycle; VCO Divider
Used; Duty Cycle Correction On (DCCOFF = 0); VCO
Divider Input Duty Cycle = X%
VCO
Divider
D
X.1
D
X.2
Output
Duty Cycle
N
X.1
+ M
X.1
+ 2 N
X.2
+ M
X.2
+ 2
Even 1 1 50%
Odd = 3 1 1 (1 + X%)/3
Odd = 5 1 1 (2 + X%)/5
Even
Even
(N
X.1
= M
X.1
)
1 50%
Odd
Even
(N
X.1
= M
X.1
)
1 50%
Even
Odd
(M
X.1
= N
X.1
+ 1)
1 50%
Odd = 3
Odd
(M
X.1
= N
X.1
+ 1)
1
(3N
X.1
+ 4 + X%)/
(6N
X.1
+ 9)
Odd = 5
Odd
(M
X.1
= N
X.1
+ 1)
1
(5N
X.1
+ 7 + X%)/
(10N
X.1
+ 15)
Even
Even
(N
X.1
= M
X.1
)
Even
(N
X.2
= M
X.2
)
50%
Odd
Even
(N
X.1
= M
X.1
)
Even
(N
X.2
= M
X.2
)
50%
Even
Odd
(M
X.1
= N
X.1
+ 1)
Even
(N
X.2
= M
X.2
)
50%
Odd
Odd
(M
X.1
= N
X.1
+ 1)
Even
(N
X.2
= M
X.2
)
50%
Even
Odd
(M
X.1
= N
X.1
+ 1)
Odd
(M
X.2
= N
X.2
+ 1)
50%
Odd = 3
Odd
(M
X.1
= N
X.1
+ 1)
Odd
(M
X.2
= N
X.2
+ 1)
(6N
X.1
N
X.2
+ 9N
X.1
+
9N
X.2
+ 13 + X%)/
(3(2N
X.1
+ 3)
(2N
X.2
+ 3))
Odd = 5
Odd
(M
X.1
= N
X.1
+ 1)
Odd
(M
X.2
= N
X.2
+ 1)
(10N
X.1
N
X.2
+ 15N
X.1
+
15N
X.2
+ 22 + X%)/
(5(2 N
X.1
+ 3)
(2 N
X.2
+ 3))