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Cyclone V PLLs
PLLs provide robust clock management and synthesis for device clock management, external system clock
management, and high-speed I/O interfaces.
The Cyclone V device family contains fractional PLLs that can function as fractional PLLs or integer PLLs.
The output counters in Cyclone V devices are dedicated to each fractional PLL that support integer or
fractional frequency synthesis.
The Cyclone V devices offer up to 8 fractional PLLs in the larger densities.
Table 4-7: PLL Features in Cyclone V Devices
Support
Feature
Yes
Integer PLL
Yes
Fractional PLL
9
C
output counters
1 to 512
M
,
N
,
C
counter sizes
2 single-ended and 1 differential
Dedicated external clock outputs
4 single-ended or 4 differential
Dedicated clock input pins
Single-ended or differential
External feedback input pin
Yes
(5)
Spread-spectrum input clock tracking
Yes
Source synchronous compensation
Yes
Direct compensation
Yes
Normal compensation
Yes
Zero-delay buffer compensation
Yes
External feedback compensation
Yes
LVDS compensation
78.125 ps
(6)
Phase shift resolution
Yes
Programmable duty cycle
Yes
Power down mode
PLL Physical Counters in Cyclone V Devices
The physical counters for the fractional PLLs are arranged in the following sequences:
• Up-to-down
(5)
Provided input clock jitter is within input jitter tolerance specifications. The modulation frequency of the input
clock is below the PLL bandwidth which is specified in the Fitter report.
(6)
The smallest phase shift is determined by the voltage-controlled oscillator (VCO) period divided by eight. For
degree increments, the Cyclone V device can shift all output frequencies in increments of at least 45°. Smaller
degree increments are possible depending on the frequency and divide parameters.
Clock Networks and PLLs in Cyclone V Devices
Altera Corporation
CV-52004
Cyclone V PLLs
4-16
2014.01.10