HFC-S Cologne Chip AG, HFC-S Datasheet - Page 44

• Manufacturer Part Number: HFC-S
• Description: Isdn S/t HDLC Basic Rate Controller
• Manufacturer: Cologne Chip AG

7
In order to comply to the physical requirements of ITU-T recommendation I.430 and considering the
national requirements concerning overvoltage protection and electromagnetic compatibility (EMC),
the HFC-S needs some additional circuitry, which are shown in the following figures.
7.1
Figure 9: External receiver circuitry
Part list
R1, R1'
R2, R2'
R3
R7
C1
C2, C2' optional 22 - 47 pF
C3, C3' optional 10 pF
C2 - C3' are for reduction of high frequency input noise and should be located as close as possible to
the HFC-S.
D1, D2
D3, D4
S/T module
VDD
March 1997
ADJ_LEV
LEV_R2
LEV_R1
R2
R1
S/T interface circuitry
External receiver circuitry
R2
R1
R1´
R2´
33 k
100 k
1 M
1.8 M
47 nF
1N4148 or LL4148
1N4148 or LL4148
see Table 4 on page 46
+5 V (if VDD
R4
C3
C2
C2´
C3´
R7
C1
R3
GND
VDD
+5V R7 and R3 must be changed)
R5
R5´
GND
R4
R5, R5'
R6, R6'
D1
D3
D2
D4
3.9 k
4.7 k
4.7 k
VDD
R6
R6´
10
11
12
S/T module
16
14
5
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HFC-S
RX +
RX -
S/T side