Xilinx Spartan-3A DSP FPGA Series, Technical Reference Manual

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Hardware overview
19
Mictor pin FPGA pin Description Mictor pin FPGA pin Description
37 H12 SE_IO_14 38 D8 SE_IO_30
39 NC GND 40 NC GND
41 NC GND 42 NC GND
43 NC GND
18. Power supply devices
The power supply circuitry of the XtremeDSP Spartan-3A DSP Development Board generates 0.9 V, 1.2 V,
1.8 V, 2.5 V, 3.3 V, and 5 V, as well as one adjustable voltage to power the components of the board. The
1.2 V (PS3), 1.8 V (PS5), 2.5 V (PS2), 3.3 V (PS4), and adjustable (PS1) supplies are driven by Linear
Technology LTM4601 switching power regulators. The regulators are driven by a 753-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 device is user-configurable through the FPGA and is used for the VCCIO of the FPGA bank
connected to the FMC expansion connector. When no FMC expansion module is present, the output voltage
of PS1 should be set to 3.3 V with the I
2
C bus interface to configure the digital potentiometer (U28). See
I
2
C
bus addressing
for details.
The diagram in Figure 3 illustrates the power supply architecture and maximum current handling by each
supply. The typical operating currents are significantly below the maximum capacity. The XtremeDSP
Spartan-3A DSP Development Board is normally shipped with a 60-W power supply, which should be
suitable for most applications.
Figure 3 XtremeDSP Spartan-3A DSP Development Board power supply diagram
19. Expansion connector
This expansion connector is not used by the XtremeDSP Spartan-3A DSP Development Board.
20. FPGA
XC3SD3400A-4FGG676C Xilinx Spartan-3A DSP FPGA. The board supports configuration in several
modes: JTAG, master serial, slave serial, master SelectMAP, slave SelectMAP, byte-wide peripheral
interface (BPI) up, BPI down, and SPI modes. See
Configuration options
for details.
The FPGA is also equipped with four I/O banks. The I/O voltage applied to each bank is summarized below.