ALTPLL (Phase-Locked Loop) IP Core User Guide

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ID 683732
Date 6/16/2017
Public
Document Table of Contents
Document Table of Contents x
ALTPLL (Phase-Locked Loop) IP Core User Guide
ALTPLL (Phase-Locked Loop) IP Core User Guide x
ALTPLL Features Ports and Parameters Design Examples Document Revision History
ALTPLL Features x
Phase-Locked Loop Types of PLLs Operation Modes Output Clocks Advanced Features PLL Output Counter Cascading
Phase-Locked Loop x
Building Blocks of a PLL PLL Behavior
Types of PLLs x
Parameter Setting Total Number of PLL Available in Each Supported Device Family
Operation Modes x
Operation Modes Supported in Each Device Family Parameter Settings Determining the PLL Lock Range Expanding the PLL Lock Range Setting Up Stratix III and Stratix IV PLLs for LVDS Interfacing Simulating External Feedback Board Delay
Output Clocks x
Parameter Settings Parameter Settings When “Set up PLL in LVDS mode” Option is Enabled Summary of PLL Output Clocks
Advanced Features x
Advanced Control Signals (pllena, areset, pfdena) Clock Switchover Spread-Spectrum Clocking Gated Lock and Self-Reset Programmable Bandwidth Advanced PLL Parameters PLL Dynamic Reconfiguration Dynamic Phase Configuration
Advanced Control Signals (pllena, areset, pfdena) x
pllena areset pfdena Parameter Settings Summary of Advanced Control Signals
Clock Switchover x
Parameter Settings Summary of Automatic Clock Switchover Feature
Spread-Spectrum Clocking x
Parameter Settings Summary of Spread-Spectrum Clocking Feature
Gated Lock and Self-Reset x
Gated Lock Self-Reset on Loss of Lock Parameter Settings Calculating the Value of Gated Lock Counter Summary of Gated Lock Signals and Self-Reset on Loss of Lock
Programmable Bandwidth x
Parameter Settings Summary of Programmable Bandwidth Support
Advanced PLL Parameters x
Advanced Parameter Settings
PLL Dynamic Reconfiguration x
Parameter Settings Summary of Supported Device Families for PLL Dynamic Reconfiguration Feature
Dynamic Phase Configuration x
Supported Devices Parameter Settings Modifying the PLL Phase Shift Step Resolution Using Advanced Parameters
Ports and Parameters x
ALTPLL Input Ports ALTPLL Output Ports ALTPLL Bidirectional Port ALTPLL Parameters
Design Examples x
Design Files Design Example 1: Differential Clock Design Example 2: Generating Clock Signals
Design Example 1: Differential Clock x
Generating a 166-MHz Differential SSTL External Clock Implementing the ddr_clk Design Functional Results — Simulate the ddr_clk Design in the ModelSim®-Altera Software
Design Example 2: Generating Clock Signals x
Generating 133-MHz, 200-MHz, and 200-MHz Time-Shifted Clocks Implementing the shift_clk Design Simulating the shift_clk Design in the ModelSim-Altera Software
ALTPLL (Phase-Locked Loop) IP Core User Guide

Gated Lock

Some devices support a gated lock signal that allows you to configure a programmable 20-bit counter that holds the lock signal low for a user-specified number of input clock transitions. This is useful to eliminate the false toggling of the lock signal as the PLL begins tracking the reference clock. Gated lock allows the PLL to lock before asserting the locked signal, providing a stabilized lock signal.

An asserted locked signal indicates the PLL clock output is aligned with the PLL reference input clock. The locked signal might toggle as the PLL begins tracking the reference clock. To avoid such a false lock indication, use a gated lock signal. A gated locked signal or an ungated locked signal can feed a logic array or an output pin. When you must reset the gated counter, reset the PLL by asserting the areset signal or the pllena signal.

The following figure shows the timing waveform for gated and ungated locked signals.

Figure 11. Input and Output Ports


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