DIGITAL-LOGIC MSM800BEV, Technical User'S Manual

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DIGITAL-LOGIC AG
MSM800SEV/SEL/BEV/XEV/XEL Detailed Manual V1.7
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2.12. High Frequency Radiation (to meet EN55022)
Since the PC/104 CPU modules are very highly integrated embedded computers, peripheral lines are not
protected against radiation from the high frequency spectrum. To meet a typical EN55022 requirement, all
peripherals that go outside of the computer case must be externally filtered.
Typical signals that must be filtered:
Keyboard: KBCLK, KBDATA and VCC
Mouse: MSCLK, MSDATA and VCC
COM1/2/3/4: All serial signals must be filtered
LPT: All parallel signals must be filtered
CRT: Red, blue, green, hsynch and vsynch must be filtered
Typical signals that must not be filtered, since they are used internally:
IDE: Connected to the hard disk
Floppy: Connected to the floppy
LCD: Connected to the internal LCD
2.12.1. For Peripheral Cables:
Use a filtered version for all DSUB connectors. Select the filter specifications carefully. Place the filtered
DSUB connector directly on the front side and be sure that the shielding makes good contact with the case.
9pin DSUB connector from AMPHENOL: FCC17E09P 820pF
25pin DSUB connector from AMPHENOL: FCC17B25P 820pF
2.12.2. For Stack-Through Applications:
On each peripheral signal line that goes outside the computer case, place a serial inductivity followed by a
grounded capacitor of 100pF to 1000pF. In this case, no filtered connectors are needed. Place the filter
directly under or behind the onboard connector.
Serial Inductivity: TDK HF50ACB321611-T 100MHz, 500mA, 1206 Case
Ground Capacitor: Ceramic Capacitor with 1000pF
2.12.3. Power Supply:
Use a current-compensated dual inductor on the 5V supply.
SIEMENS B82721-K2362-N1 with 3.6A, 0.4mH