1st edition, 17-09-2020
7000.05070, 1st edition, 17-09-2020
7000.05070
Installation
17
Fig. 7:
Termination types
Standard: Terminating resistor R
T
= 100…130
Ω
Split termination: The terminating resistor is split symmetrically (e. g. R
T1
= R
T2
= 60
Ω
).
The capacitor C (4.7...10 nF) discharges common-mode currents to ground. This leads to
an increased interference resistance of the signal transmission.
AC termination: A capacitor C in series with the terminating resistor R
T
can reduce the
power consumption and thus the power loss in R
T
. The value of the capacitor must be
adjusted to the clock frequency.
With twisted-pair cables, proper cable routing and shielding, transmission lengths of 5 m
and more are possible, see chap. 4.3, p. 19.
1
Standard
2
Split termination
3
AC termination
When selecting the terminating resistor R
T
, the power loss has to be considered. With a
terminating resistor R
T
of 120
Ω
, a power loss of P
V
= U
2
/R
T
= (5 V)
2
/120
Ω
≈
0,21 W
results for the termination types (1) and (2), for example.
Data
Data
R
T
Data
Data
R
T1
R
T2
C
Data
Data
R
T
C
1
2
3
