MachXO5-NX Development Board
Evaluation Board User Guide
© 2022 Lattice Semiconductor Corp. All Lattice trademarks, registered trademarks, patents, and disclaimers are as listed at
All other brand or product names are trademarks or registered trademarks of their respective holders. The specifications and information herein are subject to change without notice.
FPGA-EB-02052-1.0
17
5.
MachXO5-25 Clock Sources
The MachXO5-NX Development Board has multiple external clock options for the MachXO5-25 applications as shown in
12 MHz from U1 (FTDI)
12 MHz from U18 (FTDI)
25 MHz from U7 (SGMII PHY)
27 MHz from X4 (OSC MEM)
125 MHz from X5 (OSC MEM)
External clock source from J10 (SMA)
J8
12MHz
U1
U18
U7
X4
X5
J10
EXT_CLK
125M_OSC_OUT
27M_OSC_OUT
SGMII_CLK_OUT
U12MHz
JP10
R159
JP11
EXPCON_OSC
J11
J19
USB
USB
Clock
Generator
SMA
Figure 5.1. Onboard Clock Resources
You need take care that only 27 MHz and 125 MHz clocks are active in default after board power up. Both 12 MHz
clocks from the FT2232H FTDI U1 and U18 device are not always on without some hardware configuration. 25 MHz of
SGMII and external clock need source from other devices. Refer to
for those clock utilization and enable
conditions.
Table 5.1. Input Clock Options
Clock
Frequency
Net Name
MachXO5-25
Ball Location
Clock
Source
Always
On?
Enable Conditions
12 MHz
12MHZ
E16
U1
No
Need add R159 and JP11. USB header J11 connected
with power on.
12 MHz
U12MHZ
E14
U18
No
Need add JP10. USB header J19 connected with
power on.
25 MHz
SGMII_CLK_OUT
T7
U7
No
Power on. U7 populated and enabled.
27 MHz
27M_OSC
B1
X4
Yes
Power on. Force 27M_EN high if R161 populated.
125 MHz
125M_OSC
V1
X5
Yes
Power on. Force 125M_EN high if R232 populated.
Customer
EXT_CLK
D19
J10
No
Need add J10. Connect to external clock generator
through SMA cable.