Texas Instruments SN74ALVTH16821DLR

Overview

SN74ALVTH16821DLR 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 inputs eliminating external pull resistors, and high-drive capability (–32/64 mA at 3.3 V). Used in backplane data latching and mixed-voltage bus bridging applications.

For engineers reviewing the SN74ALVTH16821DLR datasheet, SN74ALVTH16821DLR pinout, SN74ALVTH16821DLR application, or SN74ALVTH16821DLR equivalent, this page delivers verified electrical specs, thermal performance (θJA = 74°C/W), timing parameters (tPLH ≤ 3.5 ns @ 3.3 V), power-up high-impedance behavior, and live-insertion support - all critical for high-speed bus interface design and voltage translation.

Technical Context

The SN74ALVTH16821DLR 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 signal operation: inputs tolerate 5-V logic levels with VCC as low as 2.3 V.

Auto3-State logic disables outputs when VO exceeds VCC + 0.5 V, preventing bus contention during hot-swap events. Distributed VCC/GND pinning and flow-through layout minimize switching noise, and bus-hold circuitry (IBHL = 75 µA, IBHH = –75 µA @ 3 V) actively maintains valid logic states on floating data inputs without external components.

Key Specifications

Pinout & Package

SN74ALVTH16821DLR uses a 56-pin 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 SN74ALVCH16821GR and SN74LVC16374ADGGR, the SN74ALVTH16821DLR uniquely combines 5-V input tolerance, Auto3-State, bus-hold, and SSOP packaging - making it the sole option for robust, component-minimized mixed-voltage bus latching in space-constrained industrial modules.

Availability

SN74ALVTH16821DLR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, telecom backplane latching, and hot-swappable module interface applications requiring stable component supply and long-term obsolescence management.

Supply support for SN74ALVTH16821DLR 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 SN74ALVTH16821DLR belongs to TI's ALVTH advanced bus-interface logic family, engineered specifically for mixed-voltage system bridging, live insertion, and noise-immune parallel bus operation in industrial and communications infrastructure.

FAQ

What is the operating temperature range for the SN74ALVTH16821DLR?

The SN74ALVTH16821DLR is characterized for operation from –40°C to 85°C, matching industrial-grade requirements. This range is confirmed in the SCES078E datasheet Section "Recommended Operating Conditions" for the SN74ALVTH16821 variant, and applies directly to the DL-package SN74ALVTH16821DLR. The device maintains full timing and drive specifications across this span without derating.

Does the SN74ALVTH16821DLR support 5-V input signals when powered at 3.3 V?

Yes, the SN74ALVTH16821DLR supports 5-V input signals with VCC as low as 2.3 V. Per the datasheet's "Mixed-Mode Signal Operation" feature and absolute maximum ratings (VI up to 7 V), its inputs tolerate 5.5-V logic levels while operating at 3.3-V VCC - enabling direct interfacing to legacy 5-V peripherals without external level shifters. This is a core specification of the ALVTH family.

How does the bus-hold feature work on the SN74ALVTH16821DLR, and what current does it provide?

The SN74ALVTH16821DLR integrates active bus-hold circuitry on all data inputs (1D1–1D10, 2D1–2D10), which sources or sinks current to maintain the last-valid logic state when inputs float. At VCC = 3 V, it provides ±75 µA sustaining current (IBHL = 75 µA, IBHH = –75 µA), eliminating the need for external 10-kΩ pullup/pulldown resistors and reducing board space and BOM cost.

What is the thermal performance of the SN74ALVTH16821DLR in its DL package?

The SN74ALVTH16821DLR in the DL (SSOP-56) package has a junction-to-ambient thermal resistance (θJA) of 74°C/W, as specified in the "Absolute Maximum Ratings" table of SCES078E. This value assumes standard JEDEC 2S2P test conditions and enables accurate thermal derating for continuous operation in enclosed industrial enclosures or stacked PCB assemblies.

Can the SN74ALVTH16821DLR be used as a single 20-bit latch or must it operate as two 10-bit sections?

The SN74ALVTH16821DLR can be configured either way: as one 20-bit flip-flop using shared clock and OE control, or as two independent 10-bit sections with separate 1CLK/1OE and 2CLK/2OE signals. The functional diagram and truth table in the SCES078E datasheet explicitly confirm this dual-mode operation, giving designers flexibility in partitioning data paths without adding logic gates.