AD9517-2ASLASHPCBZ datasheet(45/80 Pages) AD

45 / 80 page

Data Sheet

AD9517-2

Rev. F | 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 DX.Y must be set as MX.Y = NX.Y (low cycles = high

cycles).



An odd DX.Y must be set as MX.Y = NX.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

DX.1

DX.2

Output

Duty Cycle

NX.1 + MX.1 + 2

NX.2 + MX.2 + 2

Even

50%

Odd = 3

33.3%

Odd = 5

40%

Even

Even, odd

(NX.1 + 1)/

(NX.1 + MX.1 + 2)

Odd

Even, odd

(NX.1 + 1)/

(NX.1 + MX.1 + 2)

Even

Even, odd

(NX.2 + 1)/

(NX.2 + MX.2 + 2)

Odd

Even, odd

(NX.2 + 1)/

(NX.2 + MX.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

DX.1

DX.2

Output

Duty Cycle

NX.1 + MX.1 + 2

NX.2 + MX.2 + 2

50%

Even, odd

(NX.1 + 1)/

(NX.1 + MX.1 + 2)

Even, odd

(NX.1 + 1)/

(NX.1 + MX.1 + 2)

50%

Even, odd

(NX.2 + 1)/

(NX.2 + MX.2 + 2)

Even, odd

(NX.2 + 1)/

(NX.2 + MX.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

DX.1

DX.2

Output

Duty

Cycle

NX.1 + MX.1 + 2

NX.2 + MX.2 + 2

Even

50%

Odd

50%

Even

Even (NX.1 = MX.1)

50%

Odd

Even (NX.1 = MX.1)

50%

Even

Odd (MX.1 = NX.1 + 1)

50%

Odd

Odd (MX.1 = NX.1 + 1)

50%

Even

Even (NX.1 = MX.1)

Even (NX.2 = MX.2)

50%

Odd

Even (NX.1 = MX.1)

Even (NX.2 = MX.2)

50%

Even

Odd (MX.1 = NX.1 + 1)

Even (NX.2 = MX.2)

50%

Odd

Odd (MX.1 = NX.1 + 1)

Even (NX.2 = MX.2)

50%

Even

Odd (MX.1 = NX.1 + 1)

Odd (MX.2 = NX.2 + 1)

50%

Odd

Odd (MX.1 = NX.1 + 1)

Odd (MX.2 = NX.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

DX.1

DX.2

Output

Duty Cycle

NX.1 + MX.1 + 2

NX.2 + MX.2 + 2

Even

50%

Odd = 3

(1 + X%)/3

Odd = 5

(2 + X%)/5

Even

(NX.1 = MX.1)

50%

Odd

Even

(NX.1 = MX.1)

50%

Even

Odd

(MX.1 = NX.1 + 1)

50%

Odd = 3

Odd

(MX.1 = NX.1 + 1)

(3NX.1 + 4 + X%)/

(6NX.1 + 9)

Odd = 5

Odd

(MX.1 = NX.1 + 1)

(5NX.1 + 7 + X%)/

(10NX.1 + 15)

Even

(NX.1 = MX.1)

Even

(NX.2 = MX.2)

50%

Odd

Even

(NX.1 = MX.1)

Even

(NX.2 = MX.2)

50%

Even

Odd

(MX.1 = NX.1 + 1)

Even

(NX.2 = MX.2)

50%

Odd

(MX.1 = NX.1 + 1)

Even

(NX.2 = MX.2)

50%

Even

Odd

(MX.1 = NX.1 + 1)

Odd

(MX.2 = NX.2 + 1)

50%

Odd = 3

Odd

(MX.1 = NX.1 + 1)

Odd

(MX.2 = NX.2 + 1)

(6NX.1NX.2 + 9NX.1 +

9NX.2 + 13 + X%)/

(3(2NX.1 + 3)

(2NX.2 + 3))

Odd = 5

Odd

(MX.1 = NX.1 + 1)

Odd

(MX.2 = NX.2 + 1)

(10NX.1NX.2+ 15NX.1 +

15NX.2 + 22 + X%)/

(5(2 NX.1 + 3)

(2 NX.2 + 3))

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