Texas Instruments SN74ALVCH16821DGGR

Overview

SN74ALVCH16821DGGR from Texas Instruments is a 3.3-V, 20-bit bus-interface D-type flip-flop with 3-state outputs, designed for 1.65-V to 3.6-V V_CC operation. It supports dual 10-bit or single 20-bit configuration, features edge-triggered clocking on CLK↑, buffered OE control, and bus-hold circuitry eliminating external pullup/pulldown resistors - used in high-density data bus buffering and level-shifting applications in telecom backplanes and industrial controllers.

For engineers reviewing the SN74ALVCH16821DGGR datasheet, SN74ALVCH16821DGGR pinout, SN74ALVCH16821DGGR application, or SN74ALVCH16821DGGR equivalent, key selection criteria include its 56-pin TSSOP package, ±24-mA output drive at 3 V, 150-MHz max clock frequency, bus-hold input retention, and compatibility with mixed-voltage system interfacing across 1.65–3.6-V domains.

Technical Context

This device implements two independent 10-bit D-type flip-flop banks, each with dedicated clock (1CLK/2CLK) and output-enable (1OE/2OE) inputs. Data is latched on the positive edge of CLK; OE controls high-impedance state without affecting internal latch operation - enabling concurrent data loading while outputs remain tri-stated.

It integrates active bus-hold circuitry on all data inputs (1D1–1D10, 2D1–2D10), maintaining valid logic states on unused or floating inputs. Absolute maximum ratings include 4.6-V supply tolerance and ±50-mA continuous output current, with latch-up immunity exceeding 250 mA per JESD 17.

Key Specifications

Pinout & Package

TSSOP-56 (DGG) package: 13.9 mm × 6.1 mm body, 0.5-mm lead pitch, 1.2-mm max height, RoHS-compliant NiPdAu finish, MSL Level-1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALVCH16821DGGR, SN74ALVCH16820DGGR reduces bit count but retains full feature parity, while SN74LVC16374DGGR trades bus-hold and latch-up immunity for broader industry adoption - making SN74ALVCH16821DGGR optimal for high-reliability, floating-input scenarios in dense backplanes.

Availability

SN74ALVCH16821DGGR is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLC I/O modules, and FPGA-based embedded systems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for SN74ALVCH16821DGGR 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74ALVCH16821DGGR belongs to TI's Widebus™ family of advanced bus-interface logic, engineered specifically for high-speed, low-voltage, noise-immune data path buffering in multi-voltage system architectures.

FAQ

What is the recommended power-up sequence for SN74ALVCH16821DGGR to ensure high-impedance outputs?

TI recommends tying OE inputs to V_CC through a pullup resistor during power-up or power-down to guarantee outputs remain in high-impedance state. For SN74ALVCH16821DGGR, minimum resistor value depends on driver sink capability - typically 4.7 kΩ to 10 kΩ suffices given its ±5-µA input leakage at 3.6 V. This prevents bus contention before system initialization completes.

Does SN74ALVCH16821DGGR support mixed-voltage operation between its inputs and outputs?

Yes, SN74ALVCH16821DGGR supports mixed-voltage operation: inputs tolerate VI up to V_CC + 0.5 V (max 4.6 V), and outputs swing rail-to-rail within V_CC. When V_CC = 2.5 V, it accepts 3.3-V inputs safely, and when V_CC = 3.3 V, it drives 3.3-V logic levels - enabling seamless interfacing between 1.8-V, 2.5-V, and 3.3-V subsystems without external level shifters.

How does the bus-hold circuitry in SN74ALVCH16821DGGR affect input termination design?

The bus-hold circuitry in SN74ALVCH16821DGGR actively maintains the last valid logic state on undriven inputs using ±75 µA hold current at 3 V, making external pullup/pulldown resistors unnecessary and potentially harmful. TI explicitly warns against combining bus-hold with external terminations, as they conflict and may cause excessive current draw or metastability.

What is the maximum capacitive load SN74ALVCH16821DGGR can drive while maintaining 150-MHz operation?

SN74ALVCH16821DGGR maintains 150-MHz operation with CL ≤ 50 pF, as verified in TI's switching characteristics table under "Operating Characteristics" (C_pd = 40 pF typical at 3.3 V, 10 MHz). Driving >50-pF loads degrades edge rate and increases propagation delay - for heavier loads, derate clock frequency or add local series termination to preserve signal integrity.

Is SN74ALVCH16821DGGR pin-compatible with earlier-generation TI 20-bit flip-flops like SN74ALVCH16821DL?

Yes, SN74ALVCH16821DGGR is pin-compatible with SN74ALVCH16821DL: both use 56-pin layouts with identical pin functions and assignments (per TI's DGG and DL package drawings). The only differences are package type (TSSOP vs. SSOP), thermal impedance (48°C/W vs. 56°C/W), and packaging format (tape-and-reel vs. tube) - allowing direct substitution in existing PCB designs with no layout changes required.