Texas Instruments SN74ALVTH16821DL

Overview

SN74ALVTH16821DL from Texas Instruments is a 20-bit bus-interface D-type flip-flop with 3-state outputs, designed for 2.5-V/3.3-V operation and TTL-level interfacing to 5-V systems. It features edge-triggered storage on CLK↑, bus-hold on all data inputs, auto-3-state detection, and high-drive capability (–32/64 mA at 3.3 V). Used in backplane and motherboard bus buffering applications requiring mixed-voltage signal integrity.

For engineers reviewing the SN74ALVTH16821DL datasheet, SN74ALVTH16821DL pinout, SN74ALVTH16821DL application, or SN74ALVTH16821DL equivalent, this page delivers verified electrical specs, thermal performance (θ_JA = 74°C/W), timing behavior (f_CLK = 150 MHz), power-up high-impedance safety, and live-insertion support - all critical for industrial control and telecom board design.

Technical Context

The SN74ALVTH16821DL implements two independent 10-bit sections, each with separate clock (1CLK/2CLK) and output-enable (1OE/2OE) controls, enabling flexible 10-bit or consolidated 20-bit operation. Its Advanced BiCMOS Technology (ABT) architecture delivers low static power dissipation while supporting mixed-mode signaling: 5-V-tolerant inputs/outputs with V_CC as low as 2.3 V.

It integrates distributed V_CC/GND pins and flow-through pinout to minimize switching noise, plus bus-hold circuitry eliminating external pullup/pulldown resistors. Power-off output disable and <1.2-V power-up high-impedance state prevent bus conflicts during hot-swap events.

Key Specifications

Pinout & Package

SN74ALVTH16821DL uses a 56-pin Plastic Shrink Small-Outline Package (SSOP, DL), 11.4 mm × 7.9 mm × 1.75 mm body, JEDEC MO-194 compliant, with gull-wing leads and 0.5-mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALVTH16821DL, SN74ALVCH16821GR trades bus-hold and higher drive for smaller footprint, while SN74LVC16373ADGGR sacrifices voltage flexibility and bit-width for lower unit cost - making SN74ALVTH16821DL uniquely suited for robust, mixed-voltage, high-speed bus isolation.

Availability

SN74ALVTH16821DL is available at Aetrix Electronics and suitable for industrial control systems, telecom infrastructure hardware, and embedded computing platforms requiring stable component supply, long-lifecycle assurance, and guaranteed obsolescence management.

Supply support for SN74ALVTH16821DL 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 for industrial and communications markets.

The SN74ALVTH16821DL belongs to TI's ALVTH widebus™ logic family, engineered specifically for high-speed, mixed-voltage bus interfacing in mission-critical systems where signal integrity, hot-swap safety, and long-term supply stability are mandatory.

FAQ

What is the maximum clock frequency supported by the SN74ALVTH16821DL?

The SN74ALVTH16821DL supports a maximum clock frequency of 150 MHz across its full operating temperature range (–40°C to +85°C) and supply voltage range (2.3 V to 3.6 V), as verified in TI's SCES078E datasheet timing tables for both 2.5-V and 3.3-V conditions. This enables use in high-bandwidth parallel interfaces such as memory-mapped I/O and FPGA co-processor links.

Does the SN74ALVTH16821DL require external pullup or pulldown resistors on its data inputs?

No. The SN74ALVTH16821DL integrates active bus-hold circuitry on all 20 data inputs (1D1–1D10, 2D1–2D10), which maintains valid logic levels on floating inputs without external components. This eliminates the need for 10 kΩ pull resistors, reducing BOM cost and PCB area - a key advantage confirmed in the device's functional description and electrical characteristics tables.

Can the SN74ALVTH16821DL safely interface between 3.3-V and 5-V logic domains?

Yes. The SN74ALVTH16821DL supports mixed-mode signal operation: its inputs and outputs tolerate up to 5.5 V regardless of V_CC (2.3–3.6 V), enabling direct connection to 5-V peripherals while powered from a 3.3-V rail. This capability is explicitly documented in the "Recommended Operating Conditions" and "Absolute Maximum Ratings" sections of the SCES078E datasheet.

What thermal performance can be expected from the SN74ALVTH16821DL in its DL package?

The SN74ALVTH16821DL in the DL (SSOP-56) package has a specified junction-to-ambient thermal resistance (θ_JA) of 74°C/W, measured per JESD 51. This value allows accurate junction temperature estimation under load - for example, at 5 mA ICC and 64 mA I_OL, peak power dissipation remains within safe limits for continuous operation at +85°C ambient.

How does the SN74ALVTH16821DL handle power-up and power-down sequencing?

The SN74ALVTH16821DL enters a high-impedance state automatically when V_CC drops below 1.2 V, preventing bus conflicts during power-up/down. This behavior is intrinsic to the device and requires no external circuitry. OE pins remain functional above 1.2 V, allowing precise control of output states once supply stabilizes - a feature validated in the "Functional Description" and "Absolute Maximum Ratings" sections.