Texas Instruments SN74ABT821ADW

Overview

SN74ABT821ADW from Texas Instruments is a 10-bit bus-interface D-type flip-flop with 3-state outputs, designed for high-drive bidirectional bus buffering in 5-V systems. It features edge-triggered clocking (CLK), independent output-enable (OE) control, ±32-mA/64-mA drive capability, and operates from –40°C to 85°C in a 24-pin SOIC (DW) package. It is used in I/O port expansion and parity-enabled bus drivers.

For engineers reviewing the SN74ABT821ADW datasheet, SN74ABT821ADW pinout, SN74ABT821ADW application, or SN74ABT821ADW equivalent, key selection criteria include guaranteed 125-MHz clock frequency, low-output ground bounce (<1 V), high-impedance state during power-up/down, and compatibility with TTL-level control signals.

Technical Context

This device implements ten independent positive-edge-triggered D-type flip-flops with a shared clock (CLK) and a common 3-state output-enable (OE) input. Each flip-flop latches true data on CLK's rising edge and holds it until the next active clock transition.

The OE input controls all ten Q outputs simultaneously, placing them in high-impedance (Z) state without affecting internal latch operation - enabling data retention or update while outputs are disabled. The device uses EPIC-II^B BiCMOS technology to achieve low power dissipation while delivering high current drive (–32 mA IOH, 64 mA IOL).

Key Specifications

Pinout & Package

SN74ABT821ADW is housed in a 24-pin plastic small-outline integrated circuit (SOIC) package (DW), 7.5 mm wide, with 1.27 mm pitch and gull-wing leads. Pin 1 is marked by a beveled corner or notch orientation per JEDEC MO-153.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit bus-interface flip-flop applications.

Compared with SN74ABT821ADW, SN74ABT821ADWR offers identical performance in a high-volume tape-and-reel format, while SN74ABT273DW provides 8-bit functionality in the same package - making it a space-constrained alternative rather than a drop-in replacement.

Availability

SN74ABT821ADW is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory-mapped I/O expansion, and parity-enabled bus driver designs requiring stable component supply across extended product lifecycles.

Supply support for SN74ABT821ADW 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 logic solutions, with decades of heritage in high-reliability interface ICs.

The SN74ABT821A belongs to TI's ABT logic family - engineered for 5-V bus interfacing with high drive, low noise, and robust power sequencing behavior in industrial and computing systems.

FAQ

What is the maximum clock frequency supported by SN74ABT821ADW?

The SN74ABT821ADW supports a maximum clock frequency of 125 MHz under recommended operating conditions (VCC = 5 V, TA = 25°C, CL = 50 pF). This rating is validated across the full industrial temperature range (–40°C to +85°C), ensuring timing integrity in real-world embedded environments where thermal variation affects propagation delays.

Does SN74ABT821ADW enter high-impedance state automatically during power-up?

Yes, SN74ABT821ADW places all outputs in high-impedance state when VCC is between 0 V and 2.1 V - covering typical power-rail ramp-up/down profiles. However, above 2.1 V, OE must be actively pulled high (e.g., via a resistor to VCC) to guarantee high-Z behavior, as internal circuitry no longer enforces it unconditionally.

Can SN74ABT821ADW drive a 50-pF load at 125 MHz without signal degradation?

Yes - the SN74ABT821ADW's switching characteristics (tPLH/tPHL ≤ 6.2 ns, VOLP < 1 V) and 64-mA low-side drive are characterized with CL = 50 pF and 125-MHz clocking. Its EPIC-II^B BiCMOS design minimizes capacitive loading effects, enabling clean edge transitions and stable bus termination without external compensation.

What is the pin-compatible replacement for SN74ABT821ADW in the same DW package?

There is no pin-compatible 10-bit replacement within TI's ABT family that retains identical function and pinout. SN74ABT273DW shares the DW-24 package but provides only 8 bits and different pin assignments for D/Q lines. For exact pin compatibility, SN74ABT821ADWR is the only option - differing only in packaging format (tape-and-reel), not pinout or function.

How does OE affect internal latch operation in SN74ABT821ADW?

In SN74ABT821ADW, OE has no effect on internal latch operation: data can be written to or retained in the flip-flops regardless of OE state. When OE is high, outputs go high-impedance while stored data remains intact - allowing background register updates or diagnostics without disturbing the bus.