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1. Stratix® 10 Clocking and PLL Overview
2. Stratix® 10 Clocking and PLL Architecture and Features
3. Stratix® 10 Clocking and PLL Design Considerations
4. Stratix® 10 Clocking and PLL Implementation Guides
5. Clock Control Intel® FPGA IP Core References
6. IOPLL Intel® FPGA IP Core References
7. IOPLL Reconfig Intel® FPGA IP Core References
8. Stratix® 10 Clocking and PLL User Guide Archives
9. Document Revision History for the Stratix® 10 Clocking and PLL User Guide
2.2.1. PLL Features
2.2.2. PLL Usage
2.2.3. PLL Architecture
2.2.4. PLL Control Signals
2.2.5. Clock Feedback Modes
2.2.6. Clock Multiplication and Division
2.2.7. Programmable Phase Shift
2.2.8. Programmable Duty Cycle
2.2.9. PLL Cascading
2.2.10. Clock Switchover
2.2.11. PLL Reconfiguration and Dynamic Phase Shift
2.2.12. PLL Calibration
4.3.4.1. Design Example 1: .mif Streaming Reconfiguration Using IOPLL Reconfig IP Core
4.3.4.2. Design Example 2: Advanced Mode Reconfiguration Using IOPLL Reconfig IP Core
4.3.4.3. Design Example 3: Clock Gating Reconfiguration Using IOPLL Reconfig IP Core
4.3.4.4. Design Example 4: Dynamic Phase Shift Using IOPLL Reconfig IP Core
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2.2.10. Clock Switchover
The clock switchover feature allows the I/O PLL to switch between two reference input clocks. Use this feature for clock redundancy or for a dual-clock domain application where a system turns to the redundant clock if the previous clock stops running. The design can perform clock switchover automatically when the clock is no longer toggling or based on a user control signal, extswitch.
Stratix® 10 I/O PLLs support the following clock switchover modes:
- Automatic switchover—The clock sense circuit monitors the current reference clock. If the current reference clock stops toggling, the reference clock automatically switches to inclk0 or inclk1 clock.
- Manual clock switchover—Clock switchover is controlled using the extswitch signal. When the extswitch signal goes from logic high to logic low, and stays low for at least three clock cycles for the inclk being switched to, the reference clock to the I/O PLL is switched from inclk0 to inclk1, or vice-versa.
- Automatic switchover with manual override—This mode combines automatic switchover and manual clock switchover. When the extswitch signal goes low, it overrides the automatic clock switchover function. As long as the extswitch signal is low, further switchover action is blocked.