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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?
UM3085EESA Low-power Enhanced-driver Half-duplex RS485 Transceiver with IEC ESD Protection Active 5 1 1 Half 0.5 ±8 ±15 256 -7 to 12 Idle, Open, Short 0.7 -40 to 85 8/SOP Y
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Product Description
 
The UM3085EESA are ±15kV ESD-protected, high-speed transceivers for RS-485 communication that contain one driver and one receiver. These devices feature fail-safe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open, shorted or idle. This means that the receiver output will be logic high if all transmitters on a terminated bus are disabled (high impedance). The UM3085E features reduced slew-rate driver that minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission up to 500kbps. The devices feature enhanced ESD protection. All transmitter outputs and receiver inputs are protected to ±15kV using the Human Body Model and IEC61000-4-2, Air-Gap Discharge.
The transceivers typically draw 400μA of supply current when unloaded, or when fully loaded with the drivers disabled. All devices have a 1/8-unit-load receiver input impedance that allows up to 256 transceivers on the bus and are intended for half-duplex communications.
 
Features
 
- ESD Protection for RS-485 I/O Pins
  ±15kV—Human Body Model
  ±15kV—IEC61000-4-2, Air-Gap Discharge
- True Fail-Safe Receiver while Maintaining EIA/TIA-485 Compatibility
- Enhanced Slew-Rate Limiting Facilitates Error-Free Data Transmission
- 2nA Low-Current Shutdown Mode
- -7V to +12V Common-Mode Input Voltage Range
- Allows up to 256 Transceivers on the Bus
- Thermal Shutdown
- Current-Limiting for Driver Overload Protection
  
Typical Operating Circuits


 
Applications
 
- RS-485 Transceivers
- Level Translators
- Industrial-Control Local Area Networks
- Transceivers for EMI-Sensitive Applications
 
Communication Function Table
 
Table1. Transmitting                       
INPUTS
OUTPUTS
MODE
RE(______)
DE
DI
B
A
X
1
1
0
1
Normal
X
1
0
1
0
Normal
0
0
X
High-Z
High-Z
Normal
1
0
X
High-Z
High-Z
Shutdown
X=Don’t care; High-Z=High Impedance
 
Table2. Receiving
INPUTS
OUTPUTS
MODE
RE(______)
DE
A, B
RO
0
X
>-50mV
1
Normal
0
X
<-200mV
0
Normal
0
X
Inputs Open
1
Normal
1
0
X
High-Z
Shutdown
X=Don’t care; High-Z=High Impedance
 
Ordering Information
 
Part Number
Operating Temperature
Mark Code
Package Type
UM3085EESA
-40°C to +85°C
UM3085EESA
SOP8
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