Specifications

RS-422/485 Application Note 39
 Copyright B&B Electronics -- Revised October 1997
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
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EIA RS-232 Specification Summary
Parameter Conditions Min Max Units
Driver Output Voltage Open
Circuit
25 V
Driver Output Voltage Loaded
3 KΩ ≤ R
L
≤ 7
KΩ
5 15 V
V
Driver Output Resistance,
Power Off
-2V ≤ Vo ≤ 2V
300
Ω
Driver Output Short-Circuit
Current
500 mA
Driver Output Slew Rate 30
V/µs
Maximum Load Capacitance 2500 pF
Receiver Input Resistance
3V ≤ V
IN
≤ 25V
3000 7000
Ω
Receiver Input Threshold
Output = Mark
Output = Space
-3
3
V
V
EIA RS-423 Specification Summary
Parameter Conditions Min Max Units
Driver Output Voltage
Open Circuit
4
-4
6
-6
V
V
Driver Output Voltage
Loaded
R
L
= 450 Ω
3.6 6 V
Driver Output Resistance
-2V ≤ Vo ≤ 2V
50
Ω
Driver Output Short-
Circuit Current
±150 mA
Driver Output Rise and
Fall Time
Baud Rate ≤ 1K Baud
Baud Rate ≥ 1K Baud
300
30
µs
% Unit
Interval
Receiver Sensitivity
Vcm ≤ ±7V
±200 mV
Receiver Input Resistance 4000
Ω