UM488 Datasheet, PDF (1/17 Pages) Union Semiconductor, Inc. – ±15kV ESD-Protected, Fail-Safe, Slew-Rate-Limited RS-422

UM488/UM491
±15kV ESD-Protected, Fail-Safe, Slew-Rate-Limited RS-422
Transceivers in SOP8/DIP8/SOP14/DIP14
General Description
The UM488/UM491 is ±15kV electrostatic discharge (ESD)-protected, high-speed transceivers for
RS-422 communication that contain one driver and one receiver. The UM491 contains an additional
receiver and driver enable control. 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
UM488/UM491 offers higher driver output slew-rate limits, allowing transmit speeds up to 2.5Mbps.
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 375µA 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 UM488/UM491 is intended for full-duplex communications.
Applications
Features
 RS-422 Communications
 ESD Protection for RS-422 I/O Pins
 Level Translators
±15kV, Human Body Model
 Transceivers for EMI-Sensitive
 True Fail-Safe Receiver While Maintaining
Applications
EIA/TIA-422 Compatibility
 Industrial-Control Local Area Networks  Enhanced Slew-Rate Limiting Facilitates
 Error-Free Data Transmission
 1nA Low-Current Shutdown Mode
(UM491)
 Allow Up to 256 Transceivers on the Bus
Selector Guide
Part
Number
UM488
Half/Full
Duplex
full
Data
Rate
(Mbps)
2.5
Slew-
Rate
Limited
Yes
Low-
Power
Shutdown
No
Receiver/
Driver
Enable
No
UM491
full
2.5
Yes
Yes
Yes
Quiescent
Current
(µA)
375
Transceivers
On
Bus
256
Pin
Count
8
375
256
14
Ordering Information
Part Number
UM488EESA
UM488EEPA
UM491EESE
UM491EEPE
Temperature Range
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
Packaging Type
SOP8
DIP8
SOP14
DIP14
Shipping Qty
2500pcs/13 Inch Tape & Reel
50pcs/Tube
2500pcs/13 Inch Tape & Reel
50pcs/Tube
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http://www.union-ic.com Rev.04 Aug.2013
1/17