Texas Instruments SN74LVC821ADBR

Overview

SN74LVC821ADBR from Texas Instruments is a 10-bit bus-interface D-type flip-flop with 3-state outputs, designed for 1.65 V to 3.6 V VCC operation. It features edge-triggered clocking on CLK's positive transition, buffered output-enable (OE) control, and supports mixed-mode 5-V input/3.3-V VCC signal translation in I/O port and bidirectional bus driver applications.

For engineers reviewing the SN74LVC821ADBR datasheet, SN74LVC821ADBR pinout, SN74LVC821ADBR application, or SN74LVC821ADBR equivalent, key selection criteria include its 7.3 ns max propagation delay at 3.3 V, ±24 mA output drive capability, Ioff partial-power-down support, 3.3-V/5-V mixed-voltage interface compatibility, and SSOP-24 package footprint for space-constrained board layouts.

Technical Context

This device implements ten independent D-type latches synchronized to a common clock (CLK), each with true-output (Q) behavior and no inversion. The OE input controls all ten outputs simultaneously into high-impedance or active logic states without affecting internal latch operation-enabling data retention during bus isolation.

It employs LVC-series CMOS logic with TTL-compatible thresholds, supports 5.5-V-tolerant inputs regardless of VCC, and integrates Ioff circuitry to disable outputs and block reverse current during power-down-critical for hot-swap and multi-rail system designs.

Key Specifications

Pinout & Package

SN74LVC821ADBR is housed in a 24-pin SSOP (Shrink Small-Outline Package) with 0.65 mm lead pitch, 7.9 mm × 4.4 mm body size, and 1.2 mm max height per JEDEC MO-150. The package is RoHS-compliant, NIPDAU lead-finished, and rated MSL-1 (unlimited floor life at ≤30°C/60% RH).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC821APWR, SN74LVC821ADBR offers identical logic performance but in a slightly wider SSOP body optimized for manual assembly and thermal relief; versus obsolete 74LVC821ADB, SN74LVC821ADBR provides documented lifecycle assurance and updated quality screening per TI's current production standards.

Availability

SN74LVC821ADBR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, automotive body control modules, network switch data path buffering, and ATE pattern generation requiring stable component supply, consistent parametric performance, and long-term manufacturability.

Supply support for SN74LVC821ADBR 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 expertise in high-reliability interface and timing products.

The SN74LVC821ADBR belongs to TI's LVC logic family-designed specifically for low-voltage, high-speed, mixed-signal interfacing in industrial, communications, and automotive systems where voltage translation and bus integrity are critical.

FAQ

What is the maximum clock frequency supported by SN74LVC821ADBR?

The SN74LVC821ADBR supports a maximum clock frequency of 150 MHz under recommended operating conditions (VCC = 2.7 V to 3.3 V). This is derived from its minimum clock pulse width (tw) of 3.3 ns and verified in the switching characteristics table of the official datasheet SCAS304J. Timing margins must account for board-level skew and load capacitance.

Does SN74LVC821ADBR require external pull-up resistors on the OE pin?

Yes - to ensure the outputs remain in high-impedance during power-up or power-down, OE should be tied to VCC through a pull-up resistor. The minimum value depends on the driving source's current-sinking capability; TI recommends evaluating against the OE input leakage (II = ±5 µA max) and system noise margin. No internal pull-up is integrated.

Can SN74LVC821ADBR operate with a 1.8-V supply and still accept 5-V inputs?

Yes - SN74LVC821ADBR operates from 1.65 V to 3.6 V and accepts input voltages up to 5.5 V regardless of VCC level. At VCC = 1.8 V, it maintains full 5-V input tolerance, enabling robust level translation in mixed-voltage systems without external components.

What is the thermal resistance (θJA) of the SSOP-24 package used by SN74LVC821ADBR?

The SSOP-24 (DB) package of SN74LVC821ADBR has a junction-to-ambient thermal resistance (θJA) of 63°C/W, as specified in the Absolute Maximum Ratings table. This value assumes standard JEDEC 2-layer board conditions; actual performance depends on PCB copper area, airflow, and nearby heat sources.

Is SN74LVC821ADBR pin-compatible with other 10-bit LVC flip-flops like SN74LVC823A?

No - SN74LVC821ADBR is not pin-compatible with SN74LVC823A. While both are 10-bit LVC flip-flops, SN74LVC823A uses different pin assignments (e.g., separate master-reset and clock-enable pins) and lacks the dedicated OE control of SN74LVC821ADBR. Direct substitution would require PCB layout changes.