lms485 National Semiconductor Corporation, lms485 Datasheet - Page 2

• Manufacturer Part Number: lms485
• Description: 5v Low Power Rs-485 / Rs-422 Differential Bus
• Manufacturer: National Semiconductor Corporation

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Connection Diagram
Truth Table
Note:
Pin Descriptions
DRIVER SECTION
RECEIVER SECTION
Pin # I/O
1
2
3
4
5
6
7
8
*
X = Irrelevant
Z = TRI-STATE
H = High level
L = Low level
= Non Terminated, Open Input only
O
I
I
I
N/A
I/O
I/O
N/A
RE
RE
H
X
X
X
L
L
L
Name
RO
RE
DE
DI
GND
A
B
V
CC
Function
Receiver Output: If A
will be high also if the inputs (A and B) are open (non-terminated)
Receiver Output Enable: RO is enabled when RE is low; RO is in TRI-STATE when RE is high
Driver Output Enable: The driver outputs (A and B) are enabled when DE is high; they are in
TRI-STATE when DE is low. Pins A and B also function as the receiver input pins (see below)
Driver Input: A low on DI forces A low and B high while a high on DI forces A high and B low
when the driver is enabled
Ground
Non-inverting Driver Output and Receiver Input pin. Driver Output levels conform to RS-485
signaling levels
Inverting Driver Output and Receiver Input pin. Driver Output levels conform to RS-485 signaling
levels
Power Supply: 4.75V ≤ V
DE
DE
H
H
X
L
L
L
L
>
B by 200 mV, RO will be high; If A
CC
8-Pin SOIC / DIP
≤ 5.25V
Top View
DI
2
H
L
X
OPEN
≥ +0.2V
≤ −0.2V
A-B
X
20062602
*
<
A
H
L
Z
B by 200mV, RO will be low. RO
RO
B
H
H
H
Z
Z
L
L