Unregulated Power Input (J12); Regulator Option (U3) - Xilinx MultiLINX Series Hardware User's Manual

Hardware User Guide

Unregulated Power Input (J12)

+5 V Regulator Option (U3)
3-6
is ground. The power supply should provide at least 250 mA of
current to drive the LED displays.
This input provides a way to power the FPGA Demonstration Board
from an unregulated source, such as a 9 V battery or an AC adapter.
Typically, the input should be 7VDC - 12VDC at 250 mA. You must
consider the power dissipation requirements of the U3 voltage regu-
lator if the voltage input is greater than 9 V.
The J12 unregulated power input provides two holes to connect the
unregulated power source. The hole with the square pad, marked
with a "+" is the positive input. The other hole, marked with a "-" is
circuit ground. The positive input is connected through the power
on-off switch SW2–1 to U3–1, which is the optional +5 V regulator. U3
must be installed to use this input.
You can install a three terminal +5 V regulator, such as the LM2940CT
shown in the following figure. This regulator powers the demonstra-
tion board from an unregulated power supply, such as a +9 V battery.
Pin 1 (square pad) is Vin, pin 2 is ground, and pin 3 is +5 V out.
Note Insulate the metal heat sink tab of the regulator from traces and
vias on the PCB.
LM2940CT
Pin1
Figure 3-3 LM2940CT +5 V Regulator
X4692
Xilinx Development System