Board Components and Operations
UG0747 User Guide Revision 1.0
17
The following figure shows the XCVR reference clocks are interface of the PolarFire Evaluation Board.
Figure 10 •
XCVR Reference Clocks
For more information, see the Board Level Schematics document (provided separately).
4.4
Microsemi PHY (VSC8575)
The PolarFire Evaluation Board uses Microsemi physical layer (PHY) device VSC8575 for Ethernet
communications at 10/100/1000 Mbps. Device VSC8575 has four independent gigabit Ethernet
transceivers; however, the board uses only two of the transceivers. Each transceiver performs all the
PHY functions for 10BASE-T, 100BASE-TX, and 1000BASE-T full-duplex or half-duplex Ethernet on a
CAT5 twisted-pair cable. The PHY device is connected to a user-provided Ethernet cable through an
RJ45 connector with external magnetics. The VSC8575 device supports Quad SGMII for direct
connection to a PolarFire chip. The registers are configured through SPI interface, MDC\MDIO and
JTAG. Device VSC8575 supports the IEEE 1588v2 timing implementation. The ZL30364GDG2 chip
provides the 125 MHz clock and reserved clocks to VSC8575 PHY. Device ZL30364GDG2 is
configurable through the SPI interface and connected to PolarFire device.
The key features of Microsemi PHY VSC8575 are:
•
Low Power
•
IEEE 1588v2
•
Wide range of support (SGMII,QSGMII)
4.4.1
Microsemi 1588v2 (ZL30364GDG2)
The PolarFire Evaluation Board uses Microsemi ZL30364GDG2 to provide the 125 MHz clock and
reserved clocks to VSC8575 PHY. Device ZL30364GDG2 is configurable through the SPI interface and
connected to PolarFire device. The ZL30364GDG2 clock outputs are LVPECL and LVCMOS.
Key features of Microsemi PHY ZL30364GDG2 are as follows:
•
XOin: XO master clock output (24.576 MHz)
•
HPDIFF: High Performance differential output clocks (LVPECL) specifications:
•
Voltage level: 3.3 V
•
Differential output voltages, minimum 380 mV and maximum is 940 mV
•
Rise or fall time: Maximum 1 ns at the rate of 20% to 80% of the supply (3.3 V)
•
Output voltage levels:
•
High (minimum = 2.14 V and maximum = 2.42 V)
•
Low (minimum = 1.49 V and maximum = 1.75 V)
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