Texas Instruments SN74ALVCH16821DL

Overview

SN74ALVCH16821DL 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 bus-hold on all data inputs, and delivers ±24 mA output drive at 3 V - enabling direct high-drive bus interfacing without external pullup resistors in industrial backplane and memory expansion applications.

For engineers reviewing the SN74ALVCH16821DL datasheet, SN74ALVCH16821DL pinout, SN74ALVCH16821DL application, or SN74ALVCH16821DL equivalent, key selection considerations include its 56-pin SSOP (DL) package, 150-MHz maximum clock frequency, true-edge-triggered D-flip-flop behavior, bus-hold input retention, and independent 10-bit channel control via separate CLK and OE signals.

Technical Context

This device implements two synchronized 10-bit edge-triggered D-type flip-flop banks, each with dedicated clock (1CLK/2CLK) and output-enable (1OE/2OE) controls. All 20 Q outputs support 3-state logic with high-impedance disable, and internal bus-hold circuitry actively maintains valid logic states on undriven D inputs without external components.

Timing is characterized across 1.65–3.6 V supply range: setup time as low as 3.4 ns (at V_CC = 3.3 V), propagation delay of 4.5 ns (t_pd, CLK to Q), and enable/disable times under 6.6 ns (t_en/t_dis). The design complies with JESD 17 latch-up (>250 mA) and JESD 22 ESD standards (2000-V HBM, 200-V MM).

Key Specifications

Pinout & Package

SN74ALVCH16821DL uses a 56-pin Shrink Small Outline Package (SSOP-DL) with 0.5-mm pitch, 13.9 mm × 7.9 mm body size, and 1.2-mm max height - optimized for space-constrained industrial PCBs requiring thermal reliability and hand-soldering compatibility.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 20-bit bus-interface flip-flop applications.

Compared with SN74ALVCH16821DL, SN74ALVCH16820DL offers fewer bits in same package footprint, while SN74LVCH16821DL trades drive strength and speed for lower static current - making SN74ALVCH16821DL the optimal choice for high-fanout, high-frequency bus interfacing where signal integrity and timing margin are critical.

Availability

SN74ALVCH16821DL is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory expansion buffers, automated test fixture control, and high-speed data capture systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74ALVCH16821DL 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 with emphasis on industrial, automotive, and communications applications.

The SN74ALVCH16821DL belongs to TI's Widebus™ family of advanced bus-interface logic devices, engineered specifically for high-speed, low-voltage parallel bus systems requiring robust noise immunity, bus-hold stability, and precise timing control.

FAQ

What is the recommended power-up sequence for SN74ALVCH16821DL?

TI recommends tying OE inputs to V_CC through a pullup resistor during power-up or power-down to ensure outputs remain in high-impedance state until V_CC stabilizes. For SN74ALVCH16821DL, this prevents bus contention and undefined logic states. The minimum resistor value depends on the driver's current-sinking capability - typically 10 kΩ suffices for most applications. Do not leave OE floating.

Does SN74ALVCH16821DL support mixed-voltage operation between input and output sides?

Yes - SN74ALVCH16821DL operates from 1.65 V to 3.6 V and accepts input voltages from 0 to V_CC. Its VIH/VIL thresholds scale with V_CC, allowing interoperability with 1.8-V, 2.5-V, and 3.3-V logic families on the same bus. However, all inputs and outputs share the same V_CC rail; it does not support true level-shifting between independent supplies.

How does the bus-hold feature in SN74ALVCH16821DL affect power consumption?

The bus-hold circuitry in SN74ALVCH16821DL draws dynamic current only when switching states - up to ±75 µA per input at 3 V. In steady state, it consumes negligible additional current beyond standard leakage. TI specifies total ICC at 40 µA (max) with all inputs static, confirming bus-hold adds no meaningful quiescent load - ideal for low-power industrial sensors and battery-backed systems using SN74ALVCH16821DL.

Can SN74ALVCH16821DL be used as a single 20-bit register instead of two 10-bit registers?

Yes - SN74ALVCH16821DL supports both configurations. Tie 1CLK and 2CLK together and drive 1OE and 2OE jointly to operate all 20 flip-flops as one synchronized register. The device's functional diagram and timing specifications confirm identical behavior across all 20 bits, with no skew or latency penalty between banks. This mode is commonly used in memory address latching and video pixel buffering.

What is the maximum capacitive load SN74ALVCH16821DL can drive reliably at 150 MHz?

Based on TI's switching characteristics and load circuit data (CL = 50 pF, f = 10 MHz), SN74ALVCH16821DL maintains specified timing up to 50 pF per output. At 150 MHz, signal integrity depends on trace impedance and termination - TI recommends series termination near the driver and keeping trace lengths ≤10 cm for 50-pF loads. For heavier loads, derate clock frequency or add local buffering; SN74ALVCH16821DL itself does not specify absolute max CL at full speed.