Stratix V Device Handbook: Volume 2: Transceivers

ID 683779
Date 11/23/2021
Document Table of Contents Fractional PLLs

Stratix V devices provide a fractional PLL for each group of three transceiver channels.

Each fractional PLL drives one of two clock lines spanning the side of the device that can provide an input reference clock to any transmitter PLL or CDR on the same side of the device. A fractional PLL enables you to use an input reference clock in your system that is not supported by the transmitter PLL or CDR to synthesize a supported input reference clock.

Figure 48. Fractional PLL Input Clock SourcesThe following figure shows the input clock sources for the fractional PLLs located within the transceiver banks.

Note: It is not recommended to use fractional PLL in fractional mode for transceiver applications as a TX PLL or for PLL cascading.