UM3491 Datasheet, PDF (1/14 Pages) Union Semiconductor, Inc. – +3.3V Low Power，±15kV ESD-Protected, Fail-Safe, RS-422 Transceivers in SOP14/DIP14

UM3491
+3.3V Low Power，±15kV ESD-Protected, Fail-Safe, RS-422
Transceivers in SOP14/DIP14
General Description
The UM3491 is ±15kV electrostatic discharge (ESD)-protected, high-speed transceivers for
RS-422 communication that contain one driver and one receiver. The device features fail-safe
circuitry, which guarantees a logic-high receiver output when the receiver inputs are open or
shorted. This means that the receiver output will be a logic high if all transmitters on a terminated
bus are disabled (high impedance). The UM3491 allowing transmit speeds up to 10Mbps. The
device features enhanced ESD protection. All transmitter outputs and receiver inputs are
protected to ±15kV using the Human Body Model.
These transceivers typically draw 180µA of supply current when unloaded, or when fully
loaded with the drivers disabled.
The device has a 1/8-unit-load receiver input impedance that allows up to 256 transceivers on the
bus. The UM3491 is intended for full-duplex communications.
Applications
Features
z RS-422 Communications
z Level Translators
z Transceivers for EMI-Sensitive
Applications
z Industrial-Control Local Area
Networks
z ESD Protection for RS-422 I/O Pins
±15kV, Human Body Model
z True Fail-Safe Receiver While Maintaining
EIA/TIA-422 Compatibility
z Maximum Data Rate up to 10Mbps
z Error-Free Data Transmission
z 1nA Low-Current Shutdown Mode
z Allow Up to 256 Transceivers on the Bus
Pin Configurations
Top View
NC 1
RO 2
RE 3
DE 4
DI 5
GND 6
GND 7
14 VCC
R
13 NC
12 A
11 B
10 Z
D
9Y
8 NC
XX: Week Code
UM3491EESE
SOP14
XX: Week Code
UM3491EEPE
DIP14
Selector Guide
Part
Number
Half/Full
Duplex
Data
Rate
(Mbps)
Slew-
Rate
Limited
Low-
Power
Shutdown
Receiver/
Driver
Enable
UM3491 full
10
Yes
Yes
Yes
Quiescent
Current
(µA)
180
Transceivers _Pin
On
Count
Bus
256
14
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http://www.union-ic.com Rev.02 Jun.2012
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