Texas Instruments DS89C21TM

Overview

DS89C21TM from Texas Instruments is a differential CMOS line driver and receiver pair compliant with TIA/EIA-422-A (RS-422) and CCITT V.11 standards, operating at up to 20 Mbps with 2.2 ns driver transition time, 2.0 ns max driver skew, and −40°C to +85°C temperature range. It serves as a bidirectional physical-layer interface in industrial serial communication systems.

For engineers reviewing the DS89C21TM datasheet, DS89C21TM pinout, DS89C21TM application, or DS89C21TM equivalent, key selection criteria include RS-422 compliance, low-power 6 mA supply current, failsafe open-input receiver, SOIC-8 packaging, and guaranteed AC timing at 20 Mbps.

Technical Context

The DS89C21TM integrates one CMOS driver and one differential receiver in a single SOIC-8 package, with TTL/CMOS-compatible inputs (DI, RO) and ±14 V common-mode input tolerance on RI/RI*. Its driver delivers 2.0–3.0 V differential output into 100 Ω, while the receiver features 200 mV detection threshold and 20–50 mV hysteresis for noise immunity.

Propagation delays are specified at 2–10 ns (driver) and 6–30 ns (receiver), with skew tightly controlled at ≤2.0 ns (driver) and ≤4.0 ns (receiver). The device operates from 4.5 V to 5.5 V, draws 3.0–12 mA supply current depending on input state, and includes failsafe output-high behavior on open or unterminated receiver inputs.

Key Specifications

Pinout & Package

DS89C21TM is housed in an 8-pin SOIC package (Package Drawing D, JEDEC MS-012), with 1.27 mm pitch, 3.9 mm body width, and gull-wing leads suitable for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar differential line driver/receiver applications.

Compared with MAX3041ESA+ and SN65LBC179DR, DS89C21TM uniquely balances 20 Mbps capability, built-in failsafe operation, and 6 mA low-power consumption in a pin-compatible SOIC-8 package-making it optimal for space-constrained, battery-aware, or retrofit RS-422 designs requiring guaranteed timing and robustness.

Availability

DS89C21TM is available at Aetrix Electronics and suitable for industrial automation, factory instrumentation, and motor control systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for DS89C21TM 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 company headquartered in Dallas, Texas, delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The DS89C21TM belongs to TI's legacy RS-422/RS-485 interface product line, engineered specifically for high-speed, low-power, noise-immune serial communication in harsh industrial environments.

FAQ

What is the maximum data rate supported by the DS89C21TM?

The DS89C21TM supports operation up to 20 Mbps, as confirmed by TI's switching characteristics table specifying tPLHD/tPHLD propagation delays of 2–10 ns and transition times of 2.1–9 ns under 5 V supply and 25°C conditions. This rating applies across the full −40°C to +85°C operating temperature range with appropriate load and termination.

Does the DS89C21TM include built-in failsafe functionality?

Yes, the DS89C21TM incorporates a receiver failsafe feature that drives the RO output HIGH when the RI/RI* inputs are open or unterminated. This behavior is explicitly documented in the Truth Table Receiver section of the datasheet and ensures predictable logic state during cable disconnection or bus idle conditions without external biasing components.

What package type and footprint does the DS89C21TM use?

The DS89C21TM uses an 8-pin SOIC package with JEDEC MS-012 outline (Package Drawing D), 1.27 mm lead pitch, and 3.9 mm body width. Its pinout matches standard RS-422 transceiver layouts, enabling direct replacement of functionally similar devices in existing SOIC-8 footprints without PCB modification.

Is the DS89C21TM compatible with 3.3 V logic systems?

No, the DS89C21TM is specified for 4.5 V to 5.5 V supply operation only and is not 3.3 V tolerant. Its VIH minimum is 2.0 V and VIL maximum is 0.8 V, but input thresholds and output drive levels are optimized for 5 V CMOS/TTL logic families. Interfacing with 3.3 V controllers requires level-shifting circuitry to avoid undervoltage operation or signal integrity issues.

What is the common-mode input voltage range for the DS89C21TM receiver?

The DS89C21TM receiver supports a common-mode input voltage range of ±14 V on both RI and RI* inputs, as stated in the Absolute Maximum Ratings and Electrical Characteristics tables. This wide range allows reliable operation despite ground potential differences up to 28 V between transmitter and receiver nodes in electrically noisy industrial installations.