Altera Cyclone III Development Board - Manual (Page 35)

Chapter 2: Board Components 2–25
Clocking Circuitry
© March 2009 Altera Corporation Cyclone III 3C120 Development Board Reference Manual
Table 2–21 lists the board’s clock distribution system.
Oscillators
There are several on-board crystals and crystal oscillators driving reference clocks to
different devices.
Table 2–22 lists the board’s oscillators.
Table 2–20. Cyclone III Development Board Clocking Parts List
Board
Reference Description Manufacturer
Manufacturer
Part Number Manufacturer Website
Y5 50-MHz LVDS oscillator Pletronics SM5545TEX-50.00M www.pletronics.com
Y4 125-MHz LVDS oscillator Pletronics SM5545TEX-125.00M www.pletronics.com
J10, J11 SMA for external clock
input/output Lighthorse
Technologies LTI-SASF546-P26-X1 www.rfconnector.com
Y1 24-MHz crystal Abracon Corporation ABL-24.000MHZ-12 www.abracon.com
Y2 6-MHz crystal Abracon Corporation ABL-6.000MHZ-B2 www.abracon.com
X1 25-MHz crystal oscillator ECS, Inc. ECS-3953C-250-B www.ecsxtal.com
Y3 24-MHz crystal oscillator Pletronics SM5545TEX-24.00M www.pletronics.com
Table 2–21. Cyclone III Development Board Clock Distribution
Source
Schematic
Signal Name I/O Standard
Signal
Originates
From Signal Propagates To
125-MHz (Y4) oscillator clkin_125 Input Y4 Cyclone III device pin A14
50-MHz (Y5) oscillator clkin_50 Input Y5 Cyclone III device pin AH15
User input (SMA clock input) clkin_sma Input J10 Cyclone III device pin AH14
User output (SMA clock output) clkout_sma Output J11 From Cyclone III device pin AE23
25 MHz (reference clock);
This clock can change both
speed and direction depending
on the Ethernet link speed
(10/100/1000)
enet_rx_clk Input U5 Cyclone III device pin B14
24-MHz (Y3) oscillator clkin_24 Input Y3 MAX II device pin J12
(Bank 3)
6-MHz crystal XTIN /XTOUT Input Y2 FTDI USB PHY
24-MHz crystal XTALIN/XTALOUT Input Y1 Cypress USB PHY
Table 2–22. Board Oscillators
Number Frequency Description
1 6.000 MHz Crystal for FTDI USB PHY
2 24.000 MHz Crystal for Cypress USB PHY
3 24.000 MHz Crystal oscillator for MAX II CPLD
4 25.000 MHz Crystal oscillator for Ethernet PHY
5 50.000 MHz Crystal oscillator for Cyclone III FPGA PLL
6 125.000 MHz Crystal oscillator for Cyclone III FPGA PLL