UM3491 Datasheet, PDF (7/14 Pages) Union Semiconductor, Inc. – +3.3V Low Power，±15kV ESD-Protected, Fail-Safe, RS-422 Transceivers in SOP14/DIP14

UM3491
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Symbol
NC
RO
_______
RE
DE
DI
GND
GND
NC
Y
Z
B
A
NC
VCC
Function
Not Connected
________
Receiver Output. When R E is low and if A - B ≥-50mV, RO
will be high; if A - B ≤ -200mV, RO will be low.
______
Receiver Output Enable. Drive RE low to enable RO; RO is
______
______
high impedance when RE is high. Drive RE high and DE
low to enter low-power shutdown mode.
Driver Output Enable. Drive DE high to enable driver outputs.
______
These outputs are high impedance when DE is low. Drive RE
high and DE low to enter low-power shutdown mode.
Driver Input. With DE high, a low on DI forces non-inverting
output low and inverting output high. Similarly, a high on DI
forces non-inverting output high and inverting output low.
Ground
Ground
Not Connected
Non-inverting Driver Output
Inverting Driver Output
Inverting Receiver Input
Non-inverting Receiver Input
Not Connected
Positive Supply 3.135V ≤ VCC≤ 3.465V
Functions Tables
______
RE
X
X
0
1
______
RE
0
0
0
1
1
INPUTS
DE
1
1
0
0
TRANSMITTING
DI
1
0
X
X
OUTPUTS
Z
Y
0
1
1
0
High-Z
High-Z
Shutdown
RECEIVING
INPUTS
DE
A-B
X
≥-0.05V
X
≤-0.2V
X
Open/Short
1
X
0
X
OUTPUT
RO
1
0
1
High-Z
Shutdown
________________________________________________________________________
http://www.union-ic.com Rev.02 Jun.2012
7/14