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Key Specifications
Part Number Description Status Supply Voltage(Nom)(V) No. of TX No. of RX Duplex Signaling Rate(Max)(Mbps) ESD Contact (kV) ESD Air (kV) Number of Nodes Common Mode Range(V) Fail Safe ICC(Max) (mA) Operating Temperature Range(℃) Pin/Package EV Kit Available?
UM491EEPE 2.5MBPS Full-Duplex RS422 Transceiver with IEC ESD Protection Active 5 1 1 Full 2.5 ±8 ±15 256 -7 to 12 Idle, Open, Short 0.9 -40 to 85 14/DIP
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Product Description
 
The UM491 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 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 UM491 is intended for full-duplex communications.
 
Features
 
- ESD Protection for RS-422 I/O Pins
  ±15kV, Human Body Model
- True Fail-Safe Receiver While Maintaining EIA/TIA-422 Compatibility
- Enhanced Slew-Rate Limiting Facilitates
- Error-Free Data Transmission
- 1nA Low-Current Shutdown Mode
- Allow Up to 256 Transceivers on the Bus
  
Typical Operating Circuits
 
 
 
Pin Configurations
 
 

Applications
 
- RS-422 Communications
- Level Translators
- Transceivers for EMI-Sensitive Applications
- Industrial-Control Local Area Networks
 
Functions Tables
 
TRANSMITTING
INPUTS
OUTPUTS
RE(______)
DE
DI
Z
Y
X
1
1
0
1
X
1
0
1
0
0
0
X
High-Z
High-Z
1
0
X
Shutdown
 
RECEIVING
INPUTS
OUTPUT
RE(______)
DE
A-B
RO
0
X
≥-0.05V
1
0
X
≤-0.2V
0
0
X
Open/Shorted
1
1
1
X
High-Z
1
0
X
Shutdown
 
Ordering Information

Part Number
Temperature Range
Marking Code
Packaging Type
UM491EEPE
-40°C to +85°C
UM491EEPE
DIP14
 
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