FX929A Datasheet, PDF (6/44 Pages) CML Microcircuits – 4-Level FSK Modem Data Pump

4-Level FSK Modem Data Pump
1.4 External Components
FX929A
Figure 2 Recommended External Components
R1
See Section 1.5.1
R2
100k ohm ± 5%
R3
1M ohm ± 20%
R4
100k ohm ± 5%
X1
See Section 1.5.5.3
C1
0.1 µF ± 20%
C2
0.1 µF ± 20%
C3
± 20%, see Note 1
C4
± 20%, see Note 1
C5
± 5%, see Note 3
C6
± 20%, see Note 2
C7
± 20%, see Note 2
C8
± 5%, see Note 3
Note 1: The values used for C3 and C4 should be suitable for the frequency of the crystal X1. As a
guide, values (including stray capacitances) of 33pF at 1MHz falling to 18pF at 10MHz will generally
prove suitable. The 'Phase-Locked Loop Modes' part of section 1.5.5.3 discusses crystal frequency
tolerances.
Note 2: C6 and C7 values (in nano Farads) should be equal to 50000 ÷ symbol rate, e.g.
Symbol Rate
2400 symbols/second
4800 symbols/second
9600 symbols/second
C6/C7 (nF)
22.0
10.0
4.7
Note 3: C5 and C8 values (in pico Farads) should be equal to 750000 ÷ symbol rate, e.g.
Symbol Rate
2400 symbols/second
4800 symbols/second
9600 symbols/second
C5/C8 (pF)
330
150
82
© 1996 Consumer Microcircuits Limited
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D/929A/4