Texas Instruments SN74AS825ANT

Overview

SN74AS825ANT from Texas Instruments is an 8-bit bus-interface D-type flip-flop with three-state outputs, designed for bidirectional bus driving and multiuser I/O port control. It operates at 4.5–5.5 V, supports 0°C to 70°C temperature range, delivers ±24 mA high-level and 48 mA low-level output drive, and features independent OE1/OE2/OE3 enables for flexible bus arbitration in industrial backplane and legacy data acquisition systems.

For engineers reviewing the SN74AS825ANT datasheet, SN74AS825ANT pinout, SN74AS825ANT application, or SN74AS825ANT equivalent, key selection criteria include its 3-state output timing (tPZH ≤ 8 ns), undershoot-protection circuitry, power-up high-impedance state, and compatibility with TTL-level control signals in synchronous bus interface designs.

Technical Context

This device implements eight edge-triggered D flip-flops synchronized to the rising edge of CLK when CLKEN is low; CLKEN high disables clocking and holds Q outputs. CLR is asynchronous active-low, forcing all Q outputs low regardless of clock state. The flip-flops are noninverting and retain internal state even while outputs are in high-impedance mode.

Three independent output-enable inputs (OE1, OE2, OE3) operate OR-logic: any high enables normal logic output; all low places all eight Q outputs in high-impedance. Output enable does not affect internal register operation-data can be latched or held independently of output state.

Key Specifications

Pinout & Package

SN74AS825ANT uses a 24-pin plastic dual in-line package (NT), 300-mil width, with through-hole mounting. Pin numbering follows standard DIP top-view orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit bus-interface flip-flop applications.

Compared with SN74AS825ANT, SN74AS821N omits CLKEN and synchronous clock gating-reducing flexibility in dynamic bus control-but simplifies timing analysis. AM29825PC offers identical electrical behavior and pinout but differs in manufacturing source and lifecycle support, making it suitable for legacy AMD-based redesigns where TI sourcing is constrained.

Availability

SN74AS825ANT is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy data acquisition systems, and telecom line card designs requiring stable component supply, long-lifecycle support, and proven reliability in commercial-temperature environments.

Supply support for SN74AS825ANT 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74AS825ANT belongs to TI's AS-series advanced Schottky logic family, engineered for high-speed, low-power bus interfacing in legacy and upgrade systems where TTL compatibility and robust transient immunity are critical.

FAQ

What is the operating voltage range for the SN74AS825ANT?

The SN74AS825ANT operates over a supply voltage range of 4.5 V to 5.5 V. This range ensures compatibility with standard 5 V TTL systems while providing margin against rail droop and noise. Operation outside this range may cause unreliable switching or permanent damage, as specified in the absolute maximum ratings table of the SDAS020B datasheet.

Does the SN74AS825ANT support asynchronous reset?

Yes, the SN74AS825ANT features an asynchronous active-low CLR input (Pin 11). When asserted low, CLR forces all eight Q outputs to logic low immediately-regardless of CLK, CLKEN, or OE states. This function is fully characterized with a minimum pulse width of 4 ns and propagation delay of ≤15.5 ns across the operating temperature range.

How many output-enable inputs does the SN74AS825ANT have, and how do they work?

The SN74AS825ANT has three independent output-enable inputs: OE1 (Pin 1), OE2 (Pin 2), and OE3 (Pin 23). They operate with OR logic: if any one is high, all eight Q outputs enter normal logic state (driving high or low); only when all three are low do outputs go high-impedance. This design enables flexible multi-master bus control without external logic gates.

Is the SN74AS825ANT pin-compatible with other packages in the same family?

Yes, the SN74AS825ANT shares identical pinout and signal mapping with SN74AS825A in DW (SOIC) and FK (ceramic LCC) packages, as confirmed by the "TOP VIEW" diagrams and pin-number annotations in the SDAS020B datasheet. All variants use the same 24-pin assignment for D, Q, OE, CLK, CLKEN, CLR, VCC, and GND terminals.

What is the purpose of the CLKEN input on the SN74AS825ANT?

The CLKEN input (Pin 14) controls clock buffer enablement. When CLKEN is low, the internal clock buffer is active and data propagates on CLK rising edges; when CLKEN is high, the clock buffer is disabled and Q outputs hold their last latched value-effectively freezing the register without affecting OE or CLR functionality. This enables gated-clock power savings and deterministic data retention.