Datasheet

SN75177B, SN75178B
DIFFERENTIAL BUS REPEATERS
SLLS002C – D2606, JULY 1985 – REVISED FEBRUARY 1993
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
2–5
SYMBOL EQUIVALENTS
DATA SHEET PARAMETER
RS-422-A RS-485
V
O
V
oa,
V
ob
V
oa,
V
ob
|V
OD1
| V
o
V
o
|V
OD2
| V
t
(R
L
= 100 Ω) V
t
(R
L
= 54 Ω)
|V
OD3
|
V
t
(Test Termination)
Measurement 2)
∆|V
OD
| | |V
t
| – |V
t
|| | |V
t
| – |V
t
||
V
OC
|V
OS
| |V
OS
|
∆|V
OC
| |V
OS
– V
OS
| |V
OS
– V
OS
|
I
OS
|I
sa
|,|I
sb
|
I
O
|I
xa
|,|I
xb
| I
ia
,I
ib
RECEIVER SECTION
electrical characteristics over recommended ranges of common-mode input voltage, supply
voltage, and operating free-air temperature (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP
†
MAX UNIT
V
T+
Positive-going input threshold voltage V
O
= 2.7 V, I
O
= –0.4 mA 0.2 V
V
T–
Negative-going input threshold voltage V
O
= 0.5 V, I
O
= 8 mA –0.2
‡
V
V
hys
Input hysteresis (V
T+
– V
T–
) 50 mV
V
IK
Input clamp voltage at EN I
I
= –18 mA –1.5 V
V
OH
High-level output voltage
V
ID
= 200 mV,
See Figure 2
I
OH
= –400 µA,
2.7 V
V
OL
Low-level output voltage
V
ID
= –200 mV,
See Figure 2
I
OL
= 8 mA,
0.45 V
I
OZ
High im
p
edance state out
p
ut current
V
O
=04Vto24V
20
µA
I
OZ
High
-
impedance
-
state
o
u
tp
u
t
c
u
rrent
V
O
=
0
.
4
V
to
2
.
4
V
–400
µ
A
I
I
Line in
p
ut current
Other input at 0 V,
V
I
= 12 V 1
mA
I
I
Line
inp
u
t
c
u
rrent
See Note 4
V
I
= –7 V –0.8
mA
I
IH
High-level enable-input current V
IH
= 2.7 V 20 µA
I
IL
Low-level enable-input current V
IL
= 0.4 V –200 µA
r
i
Input resistance 12 kΩ
I
OS
Short-circuit output current –15 –85 mA
I
CC
Su
pp
ly current (total
p
ackage)
No load
Outputs enabled 57 70
mA
I
CC
Su ly
current
(total
ackage)
No
load
Outputs disabled 26 35
mA
†
All typical values are at V
CC
= 5 V, T
A
= 25°C.
‡
The algebraic convention, where the less-positive (more-negative) limit is designated minimum, is used in this data sheet for common-mode input
voltage and threshold voltage levels only.
NOTE 4: Refer to EIA Standard RS-422 for exact conditions.
switching characteristics, V
CC
= 5 V, T
A
= 25°C
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
t
PLH
Propagation delay time, low-to-high level output
V
ID
= –1.5 V to 1.5 V,
19 35
ns
t
PHL
Propagation delay time, high-to-low level output
ID
,
C
L
= 15 pF, See Figure 6
30 40
ns
t
PZH
Output enable time to high level
C
L
=15
p
F
See Figure 7
10 20
ns
t
PZL
Output enable time to high level
C
L
=
15
pF
,
See
Fig
u
re
7
12 20
ns
t
PHZ
Output disable time from high level
C
L
=15
p
F
See Figure 8
25 35
ns
t
PLZ
Output disable time from low level
C
L
=
15
pF
,
See
Fig
u
re
8
17 25
ns