DSP 104-plus, Справочное руководство

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158004.B00 15
The above measurements were made with a 4-chip 32M-byte SODIMM module
installed. The power consumption figures were taken after DOS had booted and the
processor was sitting idle at the DOS prompt. Power management was disabled.
Users should make their own decision concerning cooling of the processor. The
TP400 draws very little power, considering its level of performance, but is still likely to
need cooling. The TP400 dissipates up to 5W, depending on the clock speed (see
Table 1 for overall power consumption) Most of this current goes to the processor,
which may get quite hot. We recommend a heat sink and/or a fan to keep the
temperature of the processor down. The cooler a chip is the more reliable it will be. A
fan or fan and heatsink combination can be fitted to the processor, or a fan could be
provided in the enclosure along with the PC/104 boards. Connector J102 is provided
to power a +5V fan. DSP Design can provide both a passive heatsink and a
fan/heatsink combination.
As an alternative the enclosure could be designed so that part of the enclosure acted
as the heat sink. Thermal materials are available to provide a good thermal bond
between the CPU and the case.
2.2 CLOCK
A number of clock frequencies are used on the TP400. Most of these are derived
from a 14.318MHz crystal and a synthesiser chip that generates other required
frequencies.
Several 33MHz clocks are generated. These are fed to the PCI bus and to the Geode
GX1 and CS5530A chip.
The Geode GX1 incorporates its own clock multiplier that generates the processor
clock. A number of processor clock frequencies can be selected by solder links on
the board, which are set as described in Appendix B. The TP400 is fitted with a
Geode GX1 processor with a clock frequency 300MHz.
The clock synthesiser logic also generates the following clock frequencies:
•
14.318MHz for the PC/104 OSC signal.
•
8MHz for the PC/104 BUSCLOCK signal.
•
24MHz for the Super I/O chip (where it is used for serial ports, keyboard controller
and floppy disk controller).
•
48MHz for the USB ports.
•
24.5MHz for the AC97 audio codec.
•
1.8MHz for the COM3 and COM4 UARTs.
The Geode GX1 and CS5530A generate clocks for the SDRAM (synchronous
SDRAM) and graphics sub-systems.
The real-time clock, or calendar/clock, in the Super I/O chip uses a separate
32.768kHz crystal to maintain the time and date. The Ethernet chip has its own
25MHz crystal.