AD9517-2
Data Sheet
Rev. E | Page 46 of 80
Table 44. Divider 2 and Divider 3 Duty Cycle; VCO Divider
Not Used; Duty Cycle Correction On (DCCOFF = 0)
Input
Clock
Duty
Cycle
DX.1
DX.2
Output Duty Cycle
NX.1 + MX.1 + 2
NX.2 + MX.2 + 2
50%
1
50%
Even
(NX.1 = MX.1)
1
50%
X%
1
X% (High)
X%
Even
(NX.1 = MX.1)
1
50%
Odd
(MX.1 = NX.1 + 1)
1
50%
X%
Odd
(MX.1 = NX.1 + 1)
1
(NX.1 + 1 + X%)/
(2NX.1 + 3)
50%
Even
(NX.1 = MX.1)
Even
(NX.2 = MX.2)
50%
X%
Even
(NX.1 = MX.1)
Even
(NX.2 = MX.2)
50%
Odd
(MX.1 = NX.1 + 1)
Even
(NX.2 = MX.2)
50%
X%
Odd
(MX.1 = NX.1 + 1)
Even
(NX.2 = MX.2)
50%
Odd
(MX.1 = NX.1 + 1)
Odd
(MX.2 = NX.2 + 1)
50%
X%
Odd
(MX.1 = NX.1 + 1)
Odd
(MX.2 = NX.2 + 1)
(2NX.1NX.2 + 3NX.1 +
3NX.2 + 4 + X%)/
((2NX.1 + 3)(2NX.2 + 3))
Phase Offset or Coarse Time Delay (Divider 2 and Divider 3)
Divider 2 and Divider 3 can be set to have a phase offset or
delay. The phase offset is set by a combination of the bits in the
Table 45. Setting Phase Offset and Division for Divider 2 and
Divider 3
Divider
Start
High (SH)
Phase
Offset (PO)
Low
Cycles M
High
Cycles N
2
2.1
0x19C[0]
0x19A[3:0]
0x199[7:4]
0x199[3:0]
2.2
0x19C[1]
0x19A[7:4]
0x19B[7:4]
0x19B[3:0]
3
3.1
0x1A1[0]
0x19F[3:0]
0x19E[7:4]
0x19E[3:0]
3.2
0x1A1[1]
0x19F[7:4]
0x1A0[7:4]
0x1A0[3:0]
Let
Δt = delay (in seconds).
Φx.y = 16 × SH[0] + 8 × PO[3] + 4 × PO[2] + 2 × PO[1] +
1 × PO[0].
TX.1 = period of the clock signal at the input to DX.1 (in seconds).
TX.2 = period of the clock signal at the input to DX.2 (in seconds).
Case 1
When Φx.1 ≤ 15 and Φx.2 ≤ 15:
Δt = Φx.1 × TX.1 + ΦX.2 × Tx.2
Case 2
When Φx.1 ≤ 15 and Φx.2 ≥ 16:
Δt = ΦX.1 × TX.1 + (ΦX.2 16 + MX.2 + 1) × TX.2
Case 3
When ΦX.1 ≥ 16 and ΦX.2 ≤ 15:
Δt = (ΦX.1 16 + MX.1 + 1) × TX.1 + ΦX.2 × TX.2
Case 4
When ΦX.1 ≥ 16 and ΦX.2 ≥ 16:
Δt =
(ΦX.1 16 + MX.1 + 1) × TX.1 + (ΦX.2 16 + MX.2 + 1) × TX.2
Fine Delay Adjust (Divider 2 and Divider 3)
Eac
h AD9517 LVDS/CMOS output (OUT4 to OUT7) includes
an analog delay element that can be programmed to give
variable time delays (Δt) in the clock signal at that output.
DIVIDER
X.2
DIVIDER
X.1
ΔT
OUTM
BYPASS
FINE DELAY
ADJUST
CMOS
LVDS
CMOS
ΔT
OUTN
BYPASS
FINE DELAY
ADJUST
CMOS
LVDS
CMOS
OUTPUT
DRIVERS
CLK
VCO
DIVIDER
06426-
072
Figure 56. Fine Delay (OUT4 to OUT7)
The amount of delay applied to the clock signal is determined
Table 46. Setting Analog Fine Delays
OUTPUT
(LVDS/CMOS)
Ramp
Capacitors
Ramp
Current
Delay
Fraction
Delay
Bypass
OUT4
0x0A1[5:3]
0x0A1[2:0]
0x0A2[5:0]
0x0A0[0]
OUT5
0x0A4[5:3]
0x0A4[2:0]
0x0A5[5:0]
0x0A3[0]
OUT6
0x0A7[5:3]
0x0A7[2:0]
0x0A8[5:0]
0x0A6[0]
OUT7
0x0AA[5:3]
0x0AA[2:0]
0x0AB[5:0]
0x0A9[0]