AN1301 APPLICATION NOTE

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4.3 Standard termination

ST recommends a standard termination for the unused pairs on the twisted-pair interface as shown in

Figure 4. The termination basically looks like a 100 ohm load, matched to the line, which is by passed to

chassis ground. This termination is added for robustness and noise reduction.

Figure 4. Suggested Termination Circuit

5.0 CRYSTAL REQUIREMENTS

The crystal to be used with the STE101P should be a 25 MHz fundamental mode crystal operating in par-

allel resonance, connected as shown in the sample application circuit schematic (see section 7.1). The

following table shows the specifications for the crystal:

Table 1

Parameter

Units

Min

Max

Nom

Frequency

MHz

-

-

25.0

Frequency Stability

ppm

-

+ 50

-

Load Capacitance

pF

18

Shunt Capacitance

pF

8