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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?
UM491EESE 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/SOP
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Product 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.
- 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 (UM491)
- Allow up to 256 Transceivers on the Bus
Typical Application Circuit

                                 UM491 Pin Configuration and Typical Full-Duplex Operating Circuit
- RS-422 Communications
- Level Translators
- Transceivers for EMI-Sensitive Applications
- Industrial-Control Local Area Networks
Pin Configurations  

Ordering Information

Part Number
Temperature Range
Packaging Type
Shipping Qty
-40°C to +85°C
2500pcs/13 Inch
Tape & Reel
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