Texas Instruments SN65HVD78DR

Overview

SN65HVD78DR from Texas Instruments is a 3.3-V, 50-Mbps half-duplex RS-485 transceiver in an 8-pin SOIC package, featuring ±12 kV IEC 61000-4-2 contact ESD protection, 80-mV receiver hysteresis, and <2 µA standby supply current. It enables robust industrial communication over long cable runs in factory automation and motion control systems.

For engineers reviewing the SN65HVD78DR datasheet, SN65HVD78DR pinout, SN65HVD78DR application, or SN65HVD78DR equivalent, key selection criteria include signaling rate (50 Mbps), bus fault tolerance (±12 V common-mode range), thermal shutdown (170°C), low-power operation (<1 mA quiescent), and compatibility with 3.3-V/5-V logic controllers.

Technical Context

The SN65HVD78DR integrates a differential driver and receiver on a single die, operating from a 3.0–3.6-V supply. Its driver delivers ≥1.5-V differential output into 54-Ω RS-485 loads, while the receiver supports –12 V to +12 V common-mode input range and exhibits 80-mV hysteresis for noise immunity.

Control logic includes active-high DE (driver enable) and active-low RE (receiver enable), enabling precise bus direction management. Glitch-free power-up/power-down behavior prevents false bus states during supply transitions, and thermal shutdown disables outputs at 170°C junction temperature.

Key Specifications

Pinout & Package

SN65HVD78DR is housed in an 8-pin SOIC package (4.91 mm × 3.90 mm), compatible with standard surface-mount assembly processes and offering board-level drop-in replacement for legacy RS-485 transceivers.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RS-485 transceiver applications.

Compared with SN65HVD75DR and THVD1550DR, the SN65HVD78DR delivers optimal balance of speed (50 Mbps), ultra-low standby current (<2 µA), and proven industrial reliability-making it the preferred choice for new high-speed, low-power RS-485 designs requiring no additional regulation or enhanced ESD beyond IEC 61000-4-2.

Availability

SN65HVD78DR is available at Aetrix Electronics and suitable for factory automation, motion control, and telecommunications infrastructure requiring stable component supply across extended temperature and ESD stress conditions.

Supply support for SN65HVD78DR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The SN65HVD7x family was designed specifically for rugged RS-485 communication in harsh industrial environments, emphasizing ESD resilience, wide temperature operation, and interoperability with legacy 5-V logic systems.

FAQ

What is the maximum signaling rate supported by the SN65HVD78DR?

The SN65HVD78DR supports a maximum signaling rate of 50 Mbps, verified per TI's SLLSE11H datasheet Section 7.9. This is achieved with ≤6 ns driver rise/fall time and ≤15 ns propagation delay under 54-Ω RS-485 load conditions. The SN65HVD78DR maintains signal integrity at this rate across its full –40°C to +125°C operating range, making it suitable for high-throughput industrial protocols like PROFIBUS DP-V2 and EtherCAT slave interfaces.

Does the SN65HVD78DR require external ESD protection on the bus lines?

No, the SN65HVD78DR does not require external ESD protection on the A/B bus lines. It integrates ±12 kV IEC 61000-4-2 contact discharge and ±15 kV HBM protection directly on the bus pins, as confirmed in Section 7.2 of the official datasheet. This eliminates the need for discrete TVS diodes in most industrial deployments, reducing bill-of-materials cost and PCB area while maintaining compliance with IEC 61000-4-2 Level 4.

Can the SN65HVD78DR operate with a 5-V logic controller?

Yes, the SN65HVD78DR supports 5-V tolerant logic inputs (D, DE, RE), allowing direct interface with 5-V microcontrollers or FPGAs without level-shifting circuitry. As specified in Section 7.3, VIH is defined as 2 V to VCC, and absolute maximum input voltage is 5.7 V-ensuring safe operation even when VCC = 3.3 V and logic signals swing to 5 V. This simplifies mixed-voltage system design and improves signal integrity versus resistor-based translators.

What is the purpose of the thermal shutdown feature in the SN65HVD78DR?

The thermal shutdown feature in the SN65HVD78DR disables the driver outputs when the junction temperature reaches 170°C, preventing permanent damage during sustained bus short-circuits or excessive ambient temperatures. As documented in Section 7.5, this protection activates independently of supply voltage and remains engaged until TJ falls below ~155°C. It ensures fail-safe behavior in unattended industrial equipment, avoiding latch-up or thermal runaway that could compromise system safety.

How many nodes can be connected to a single SN65HVD78DR bus segment?

The SN65HVD78DR presents a 1/8-unit load to the RS-485 bus, enabling up to 256 nodes on a single segment per TIA/EIA-485 standard. Texas Instruments specifies >200 connected nodes in the device comparison table (Section 5), validated under worst-case loading with 54-Ω termination and 50-pF stub capacitance. This scalability supports large-scale distributed I/O architectures in process control and building automation without repeaters.