The SN65HVD21M offers performance exceeding typical RS-485 devices. In addition to meeting all requirements of the TIA/EIA-485-A standard, the HVD2x family operates over an extended range of common-mode voltage, and has features such as high ESD protection, wide receiver hysteresis, and failsafe operation. This family of devices is ideally suited for long-cable networks, and other applications where the environment is too harsh for ordinary transceivers.

The SN65HVD21M is designed for bidirectional data transmission on multipoint twisted-pair cables. Example applications are digital motor controllers, remote sensors and terminals, industrial process control, security stations, and environmental control systems.

The SN65HVD21M combines a 3-state differential driver and a differential receiver, which operates from a single 5-V power supply. The driver differential outputs and the receiver differential inputs are connected internally to form a differential bus port that offers minimum loading to the bus. This port features an extended common-mode voltage range making the device suitable for multipoint applications over long cable runs.

The SN65HVD21M allows up to 256 connected nodes at moderate data rates (up to 5 Mbps). The driver output slew rate is controlled to provide reliable switching with shaped transitions which reduce high-frequency noise emissions.

The receiver also includes a failsafe circuit that provides a high-level output within 250 µs after loss of the input signal. The most common causes of signal loss are disconnected cables, shorted lines, or the absence of any active transmitters on the bus. This feature prevents noise from being received as valid data under these fault conditions. This feature may also be used for Wired-Or bus signaling.

The SN65HVD21M is characterized for operation over the temperature range of -55°C to 125°C.

• Controlled Baseline
  • One Assembly/Test Site, One Fabrication Site
• Extended Temperature Performance of -55°C to 125°C
• Enhanced Diminishing Manufacturing Sources (DMS) Support
• Enhanced Product-Change Notification
• Qualification Pedigree
• Common-Mode Voltage Range (-20 V to 25 V) More Than Doubles TIA/EIA-485 Requirement
• Receiver Equalization Extends Cable Length, Signaling Rate (HVD23, HVD24)
• Reduced Unit-Load for up to 256 Nodes
• Bus I/O Protection to Over 16-kV HBM
• Failsafe Receiver for Open-Circuit, Short-Circuit and Idle-Bus Conditions
• Low Standby Supply Current 1.5-µA Max
• More Than 100 mV Receiver Hysteresis
• APPLICATIONS
  • Long Cable Solutions
    • Factory Automation
    • Security Networks
    • Building HVAC
  • Severe Electrical Environments
    • Electrical Power Inverters
    • Industrial Drives
    • Avionics

Component qualification in accordance with JEDEC and industry standards to ensure reliable operation over an extended temperature range. This includes, but is not limited to, Highly Accelerated Stress Test (HAST) or biased 85/85, temperature cycle, autoclave or unbiased HAST, electromigration, bond intermetallic life, and mold compound life. Such qualification testing should not be viewed as justifying use of this component beyond specified performance and environmental limits.