MachXO3-9400 Development Board
Evaluation Board User Guide
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FPGA-EB-02004-1.0
13
MachXO3 Clock Sources
The MachXO3-9400 Development Board has four options for the MachXO3 clock sources:
12 MHz from U1
8 MHz from U7
User defined frequency by installing an oscillator in the Y2 (DNI) footprint
Off board clock source from J10 (DNI)
The 8 MHz clock from U7 is the default clock source when building a Platform Manager design. Note that JP1 should be
installed to power the ASC device.
The 12 MHz clock from the FT2232H FTDI device is another clock source. Its use requires JP11 to be installed to connect
the 12 MHz clock signal to the MachXO3 device I/O. JP9 should not be installed to enable U1.
Table 4.1. JTAG Connections
Clock
Frequency
Signal
Name
MachXO3
Ball
Location
Clock
Source
Comments
8 MHz
ASC_CLK
L1
U7
JP1 installed, test point TP14
12 MHz
12MHz
B10
U1
JP11 installed, JP9 removed
User defined
OSC_IN
D22
Y2 (DNI)
JP4 removed and OSC_EN signal (MachXO3 ball L20) Logic 1.
User defined
OSC_IN
D22
J10 (DNI)
Y2 not installed, or OSC_EN signal (MachXO3 ball L20) Logic 0, or JP4
installed.
Additional information on using optional clock sources:
The board provides for an optional clock input for the MachXO3 from either the Oscillator (Y2) or the SMA header
(J10) as shown in
Figure 4.1
. Neither of them are populated.
Y2 should be installed by the end user and it should be a 2.5 mm x 2.0 mm 4-SMD package. This is compatible with
the ASDMB serial of the Ultra Miniature Pure Silicon™ Clock Oscillator from Abracon LLC. JP4 can be used to
disable Y2 output by pulling down OSC_EN, which can also be controlled by the L20 pin of MachXO3.
J10 should be installed by the end user. A Complementary Metal-Oxide Semiconductor (CMOS) compatible clock
can then be connected with an SMA cable.
Figure 4.1. Optional Clock Circuit Design
C97
0.1uF
OSC_IN
[4]
EXT_CLK
JP4
JUMPER
1
2
R144
0
1
2
VCCIO1
OSC_IN
Y 2
ASDMB-XX.XXXMHz
DNI
VDD
4
3
OUT
2
GND
1
Standby
R145 10K
OSC_EN
J10
SMA
DNI
1
5