Machxo3 Clock Sources; Figure 4.1. Optional Clock Circuit Design; Table 4.1. Jtag Connections - Lattice Semiconductor MachXO3-940 User Manual

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 Signal
Frequency Name
8 MHz ASC_CLK
12 MHz 12MHz
User defined OSC_IN
User defined OSC_IN
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

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.
VCCIO1
C97
0.1uF
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FPGA-EB-02004-1.0
MachXO3 Clock
Ball Source
Location
L1 U7 JP1 installed, test point TP14
B10 U1 JP11 installed, JP9 removed
D22 Y2 (DNI) JP4 removed and OSC_EN signal (MachXO3 ball L20) Logic 1.
Y2 not installed, or OSC_EN signal (MachXO3 ball L20) Logic 0, or JP4
D22 J10 (DNI)
installed.
4.1. Neither of them are populated.
R145 10K
OSC_EN
Y 2
4 1
VDD Standby
2 3
GND OUT
ASDMB-XX.XXXMHz
DNI

Figure 4.1. Optional Clock Circuit Design

Comments
JP4
2 1
JUMPER
OSC_IN
OSC_IN
R144
0
EXT_CLK
J10
SMA DNI
MachXO3-9400 Development Board
Evaluation Board User Guide
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