Texas Instruments SN74LVC821ADWG4

Overview

SN74LVC821ADWG4 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 operation. It features edge-triggered clocking on the positive CLK transition, Ioff partial-power-down support, and 5.5 V-tolerant inputs-enabling mixed-voltage interfacing in systems such as industrial I/O controllers and memory buffer interfaces.

For engineers reviewing the SN74LVC821ADWG4 datasheet, SN74LVC821ADWG4 pinout, SN74LVC821ADWG4 application, or SN74LVC821ADWG4 equivalent, key selection considerations include its 24-pin SOIC (DW) package, 7.3 ns max propagation delay at 3.3 V, 3-state output drive capability (±24 mA), Ioff-enabled power-down isolation, and compatibility with 3.3 V/5 V bidirectional bus translation.

Technical Context

This device implements ten independent edge-triggered D-type flip-flops sharing a common clock (CLK) and output-enable (OE) control. Each flip-flop captures data on the rising edge of CLK and presents true logic at Q outputs, while OE independently places all ten outputs into high-impedance without affecting internal latch state retention.

Its Ioff circuitry actively disables outputs during power-down to prevent backflow current, and input tolerance up to 5.5 V allows direct interfacing with legacy 5 V logic while operating from a 3.3 V supply-making it suitable for voltage-level bridging in FPGA-to-peripheral or microcontroller-to-bus applications.

Key Specifications

Pinout & Package

SN74LVC821ADWG4 is housed in a 24-pin SOIC (DW) package, 7.5 mm × 15.4 mm body size, with 1.27 mm lead pitch and gull-wing leads. Pin 1 is located at the top-left corner adjacent to the index notch.

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, SN74LVC821ADWG4 offers easier hand-soldering and legacy board compatibility; versus 74LVC16374ADGG, it provides superior voltage interoperability and power-down safety at the cost of channel count.

Availability

SN74LVC821ADWG4 is available at Aetrix Electronics and suitable for industrial I/O expansion, FPGA peripheral interfacing, and microcontroller bus extension requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for SN74LVC821ADWG4 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 ICs.

The SN74LVC821A family was engineered to solve voltage translation and bus-driving challenges in mixed-supply digital systems-targeting industrial automation, test equipment, and programmable logic interconnects.

FAQ

What is the maximum clock frequency supported by SN74LVC821ADWG4?

The SN74LVC821ADWG4 supports a maximum clock frequency of 150 MHz at VCC = 3.3 V, as confirmed by timing characterization in the official datasheet. This rating holds across the full operating temperature range (–40°C to +85°C) and is validated with CL = 50 pF load conditions. The device achieves this performance with a typical propagation delay (tpd) of 7.3 ns at 3.3 V.

Does SN74LVC821ADWG4 support partial-power-down mode?

Yes, SN74LVC821ADWG4 fully supports partial-power-down mode via its Ioff feature. When VCC = 0 V, the Ioff circuitry limits input/output leakage to ±10 µA, preventing damaging current backflow from live bus lines into the unpowered device-a requirement for hot-plug and modular system designs.

Can SN74LVC821ADWG4 interface directly with 5 V logic?

Yes, SN74LVC821ADWG4 accepts input voltages up to 5.5 V regardless of VCC setting (1.65–3.6 V), enabling direct connection to 5 V TTL or CMOS outputs without level-shifting components. Its outputs remain 3.3 V-compatible but tolerate 5.5 V in high-impedance state, making it ideal for bidirectional 3.3 V/5 V bus bridging.

What is the recommended pull-up resistor value for OE on SN74LVC821ADWG4?

To ensure high-impedance outputs during power-up/power-down, OE should be tied to VCC through a pull-up resistor. The minimum value depends on the driver's sink capability; TI recommends ≥10 kΩ for standard CMOS drivers. Lower values (e.g., 4.7 kΩ) improve noise immunity but increase static current draw.

Is SN74LVC821ADWG4 pin-compatible with other packages in the same family?

Yes, SN74LVC821ADWG4 shares identical pinout and functionality with all variants of the SN74LVC821A family-including SN74LVC821APWR (TSSOP), SN74LVC821ADBR (SSOP), and SN74LVC821ADGVR (TVSOP). All use the same 24-pin assignment for D inputs, Q outputs, CLK, OE, VCC, and GND, enabling drop-in replacement across packages.