Delta39K ISR
CPLD Family
Document #: 38-03039 Rev. *H
Page 12 of 86
Table 6
describes the valid phase shift options that can be
used with or without an external feedback.
Table 7
is an example of the effect of all the available divide
and phase shift options on a VCO output of 250 MHz. It also
shows the effect of division on the duty cycle of the resultant
clock. Note that the duty cycle is 50-50 when a VCO output is
divided by an even number. Also note that the phase shift
applies to the VCO output and not to the divided output.
For more details on the architecture and operation of this PLL
please refer to the application note entitled
“Delta39K PLL and
Clock Tree”.
Table 4. Valid PLL Multiply and Divide Options—without External Feedback
Input Frequency
(GCLK[0])
f
PLLI
(MHz)
DC–12.5
100–133
50–133
33.3–88.7
25–66
20–53.2
16.6–44.3
12.5–33
12.5–16.625
Valid Multiply Options
VCO Output
Frequency (MHz)
N/A
1
100–133
2
100–266
3
100–266
4
100–266
5
100–266
6
100–266
8
100–266
16
200–266
Valid Divide Options
Output Frequency (INTCLK[3:0])
f
PLLO
(MHz)
DC–12.5
6.25–133
6.25–266
6.25–266
6.25–266
6.25–266
6.25–266
6.25–266
6.25–266
Value
Value
N/A
1–6, 8, 16
1–6, 8, 16
1–6, 8, 16
1–6, 8, 16
1–6, 8, 16
1–6, 8, 16
1–6, 8, 16
1–6, 8, 16
Off-chip Clock
Frequency
DC–6.25
3.125–66
3.125–133
3.1–266
3.125–133
3.1–133
3.1–133
3.125–133
3.125–133
N/A
Table 5. Valid PLL Multiply and Divide Options—With External Feedback
Input (GCLK) Frequency
f
PLLI
(MHz)
50–133
25–66.5
16.67–44.33
12.5–33.25
12.5–26.6
12.5–22.17
12.5–16.63
Valid Multiply Options
VCO Output
Frequency (MHz)
1
100–266
1
100–266
1
100–266
1
100–266
1
125–266
1
150–266
1
200–266
Valid Divide Options
Output (INTCLK) Frequency
f
PLLO
(MHz)
100–266
50–133
33.33–88.66
25–66.5
25–53.2
25–44.34
25–33.25
Value
Value
1
2
3
4
5
6
8
Off-chip Clock
Frequency
50–133
25–66.5
16.67–44.33
12.5–33.25
12.5–26.6
12.5–22.17
12.5–16.63
Table 6. Recommended PLL Phase Shift Options
Without External Feedback
With External Feedback
0°,45°, 90°, 135°, 180°, 225°, 270°, 315°
0°
Table 7. Timing of Clock Phases for all Divide Options for a V
CO
Output Frequency of 250 MHz
Divide
Factor
(ns)
Duty Cycle%
(ns)
(ns)
1
4
40–60
0
0.5
2
8
50
0
0.5
3
12
33–67
0
0.5
4
16
50
0
0.5
5
20
40–60
0
0.5
6
24
50
0
0.5
8
32
50
0
0.5
16
64
50
0
0.5
Period
0°
45°
90°
(ns)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
135°
(ns)
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
180°
(ns)
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
225°
(ns)
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
270°
(ns)
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
315°
(ns)
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5