GTS Transceiver PHY User Guide: Agilex™ 5 FPGAs and SoCs
2.6.3.1. I/O PLL in HVIO Bank as System PLL
The I/O PLL in HVIO banks 5A/5B and 6A/6B can be used as a second system PLL. Certain devices have only one GTS transceiver bank in the device or on one side of the device. Therefore, only one system PLL is available on the side of the device. For such devices, if you configure the GTS bank to run PCIe and non-PCIe protocols requiring a System PLL, you have to use the I/OPLL for the non-PCIe protocols.
To enable the use of the I/O PLL in the HVIO banks, check the Use HVIO PLL option in the GTS PMA/FEC Direct PHY IP. The input reference clock for the I/O PLL can come from any one of the following pins in the HVIO banks 5A/5B or 6A/6B:
| GTS Bank | HVIO Bank | IOPLL Reference Clock Pin |
|---|---|---|
| 1A | 5A, 5B | PLLREFCLK1, PLLREFCLK2 |
| 1B | 5A, 5B | PLLREFCLK1, PLLREFCLK2 |
| 1C | 5A, 5B | PLLREFCLK1, PLLREFCLK2 |
| 1D | 5A, 5B | PLLREFCLK1, PLLREFCLK2 |
| 4A | 6A, 6B | PLLREFCLK1, PLLREFCLK2 |
| 4B | 6A, 6B | PLLREFCLK1, PLLREFCLK2 |
| 4C | 6A, 6B | PLLREFCLK1, PLLREFCLK2 |
| 4D | 6A, 6B | PLLREFCLK1, PLLREFCLK2 |
You must consider the following when using the I/O PLL. As the I/O PLL is different from the system PLL, you have to instantiate the I/O PLL using the IOPLL IP instead of the GTS System PLL Clocks IP. Refer to the Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs for more information. The I/O PLL in the slowest device speed grade is not capable of reaching the system PLL's maximum frequency of 1000 MHz. Refer to the device datasheet for the I/O PLL specifications. Additionally, the I/O PLL does not support the fractional mode.