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Serial Interconnections
B
Interface Characteristics
In specifying parameters for serial binary data interchange between DTE
and DCE devices, the EIA-530 standard assumes the use of balanced lines,
except for the Remote Loopback, Local Loopback, and Test Mode lines,
which are single-ended. Balanced-line data interchange is generally
employed in preference to unbalanced-line data interchange where any of
the following conditions prevail:
❏ The interconnection cable is too long for effective unbalanced
operation.
❏ The interconnection cable is exposed to extraneous noise sources
that may cause an unwanted voltage in excess of
±
1V measured
differentially between the signal conductor and circuit ground at the
load end of the cable, with a 50
Ω
resistor substituted for the
transmitter.
❏ It is necessary to minimize interference with other signals.
❏ Inversion of signals may be required (for example, plus polarity
MARK to minus polarity MARK may be achieved by inverting the
cable pair).
EIA-530 interface transmitter and receiver parameters applicable to the
MVME2603/2604 are listed in Table B-5 and Table B-6.
Table B-5. EIA-530 Interface Transmitter Characteristics
Parameter
Value
Unit
Minimum Maximum
Differential output voltage (absolute, with 100Ω
load)
2.0 V
Open circuit differential voltage output
(absolute)
6.0 V
Output offset voltage (with 100Ω load) 2.0 V
Short circuit output current (for any voltage
between −7V and +7V)
±180 mA
Power off output current (for any voltage between
−7V and +7V)
±100 µA
Output transition time (with 100Ω, 15pF load) 15 ns