EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 78

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

5–14
Zero Delay Buffer Mode
Cyclone III Device Handbook, Volume 1
Figure 5–10
this mode.
Figure 5–10. Phase Relationship Between PLL Clocks in Normal Mode
Note to
(1) The external clock output can lead or lag the PLL internal clock signals.
In zero delay buffer (ZDB) mode, the external clock output pin is phase-aligned with
the clock input pin for zero delay through the device. When using this mode, use the
same I/O standard on the input clock and output clocks to guarantee clock alignment
at the input and output pins.
Figure 5–11
in ZDB mode.
Figure 5–11. Phase Relationship Between PLL Clocks in ZDB Mode
Figure
5–10:
External PLL Clock Output
shows an example waveform of the phase relationship of the PLL clocks
shows a waveform example of the phase relationship of the PLL clocks in
at the Register Clock Port
PLL Reference
Clock at the Input pin
PLL Clock at the
Register Clock Port
External PLL Clock
Outputs
PLL Reference Clock
(1)
at the Output Pin
at the Input Pin
PLL Clock
Phase Aligned
Phase Aligned
Chapter 5: Clock Networks and PLLs in the Cyclone III Device Family
© December 2009 Altera Corporation
Clock Feedback Modes