26
www.xilinx.com
Spartan-3A DSP 3400A Edition User Guide
UG498 (v2.2) November 17, 2008
Chapter 1:
Introduction
R
15.
Power Supply Devices
The power supply circuitry of the Spartan-3A DSP 3400A Edition board generates
0.9V, 1.2V, 1.8V, 2.5V, 3.3V, and 12V, as well as two adjustable voltages to power the
components of the board. The 1.2V (PS3), 1.8V (PS5), 2.5V (PS2), 3.3V (PS4), FMC #1
adjustable (PS1) and FMC #2 adjustable (PS6) supplies are driven by Linear
Technology LTM4601 switching power regulators. The regulators are driven by a 620-
kHz clock, making them run synchronously and reducing noise caused by beat
frequencies. The clocks sent to each regulator are out of phase to reduce reflected noise
at the input.
The adjustable devices are user configurable through the FPGA and are used for the
VCCIO of the FPGA banks connected to the FMC expansion connectors. When no
FMC expansion module is present, the output voltage of PS1 should be set to 3.3V with
the I
2
C bus interface to configure the digital potentiometer (U23). See
“I2C Bus
Addressing”
for detailed information.
Figure 1-3
illustrates the power supply architecture and maximum current handling
by each supply. The typical operating currents are significantly below the maximum
capacity. The power supply delivered with the Spartan-3A DSP 3400A Edition board is
generally suitable for most applications.
G34
V5
0_LA31_N
H34
R8
0_LA30_P
G35
NC
GND
H35
R7
0_LA30_N
G36
T10
0_LA33_P
H36
NC
GND
G37
T9
0_LA33_N
H37
P8
0_LA32_P
G38
NC
GND
H38
P9
0_LA32_N
G39
NC
VADJ
H39
NC
GND
G40
NC
GND
H40
NC
VADJ
Table 1-10:
FMC #1 Expansion Connector Pin Assignments (2)
(Cont’d)
FMC Pin
FPGA Pin
Signal
FMC Pin
FPGA Pin
Signal
electronic components distributor