Diodes Incorporated PI74ALVCH16721A

Overview

PI74ALVCH16721A from Pericom Semiconductor is a 20-bit edge-triggered D-type flip-flop with 3-state outputs, designed for 2.3V–3.6V V_CC operation in high-speed bus interface applications. It features clock-enable (CLKEN) and output-enable (OE) controls, bus-hold on all data inputs, and operates across –40°C to +85°C. Typical propagation delay is 1.5 ns at V_CC = 3.3V, supporting 150 MHz clock frequency.

For engineers reviewing the PI74ALVCH16721A datasheet, PI74ALVCH16721A pinout, PI74ALVCH16721A application, or PI74ALVCH16721A equivalent, key selection criteria include 20-bit synchronous storage with independent 3-state control, bus-hold functionality eliminating external pull resistors, low ground bounce (<0.8V), and TSSOP-56 packaging compatible with high-density PCB layouts.

Technical Context

The PI74ALVCH16721A implements 20 identical D-type flip-flops, each triggered on the rising edge of CLK when CLKEN is LOW; OE independently places all Q outputs in high-impedance without affecting internal state retention. Bus-hold circuitry actively maintains last valid logic level at each D input during floating conditions.

It uses advanced 0.5 µm CMOS technology to achieve industry-leading speed at low voltage, with hysteresis on all inputs for noise immunity, and specified VOLP < 0.8V and VOHV < 2.0V at V_CC = 3.3V, TA = 25°C - critical for clean signal integrity in shared-bus systems.

Key Specifications

Pinout & Package

PI74ALVCH16721A is housed in a 56-pin plastic TSSOP (240 mil wide), designated "A" package per Pericom's ordering nomenclature. Pin spacing is 0.5 mm, body width 6.1 mm, and total height ≤1.2 mm - suitable for automated SMT assembly and space-constrained designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 20-bit latch/register applications.

Compared with SN74ALVCH16721 and 74LVC16374APAG, PI74ALVCH16721A provides unique integration of bus-hold, 20-bit width, and CLKEN gating in a single 56-pin TSSOP - reducing component count, improving noise immunity, and simplifying timing control in high-reliability industrial bus systems.

Availability

PI74ALVCH16721A is available at Aetrix Electronics and suitable for memory interface buffering, high-speed data acquisition bus management, and industrial control backplane interface applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance.

Supply support for PI74ALVCH16721A 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

Pericom Semiconductor (now part of Diodes Incorporated) specialized in high-speed interface ICs, clock management, and signal-integrity solutions for communications and computing infrastructure.

The PI74ALVCH series was engineered for low-voltage, high-speed bus interfacing - delivering fast propagation, noise-immune inputs, and integrated bus-hold to simplify system-level design in telecom, industrial, and test equipment.

FAQ

What is the purpose of the CLKEN pin on PI74ALVCH16721A?

The CLKEN (Clock Enable) pin is an active-LOW control that gates the clock input: when CLKEN is HIGH, the flip-flops ignore CLK transitions and retain current state; when LOW, rising CLK edges propagate D-input data to Q-outputs. This enables selective data capture without toggling the global clock signal, reducing system-wide switching noise.

How does bus-hold functionality eliminate external pull resistors?

Each D-input incorporates a weak feedback transistor network that detects and holds the last driven logic state (HIGH or LOW) when the input floats. With ±45 µA holding current and hysteresis, it prevents undefined logic levels during hot-swap, power sequencing, or tri-state transitions - removing the need for discrete 10–100 kΩ pull resistors and associated board space.

Can PI74ALVCH16721A operate reliably at 2.5V V_CC?

Yes - the device is fully specified from 2.3V to 3.6V. At V_CC = 2.5V, propagation delay increases to ≤3.4 ns (vs. 1.5 ns at 3.3V), and output drive reduces to ±16 mA, but all DC and AC parameters remain guaranteed across –40°C to +85°C. This supports interoperability with 2.5V ASICs and FPGAs.

Why must OE be pulled HIGH through a resistor during power-up?

OE is active-LOW; if left floating during power ramp, it may float to an indeterminate level, causing outputs to briefly enter an undefined state or oscillate. Tying OE to V_CC via a pullup resistor (minimum value set by driver sink capability, typically 4.7–10 kΩ) ensures outputs power up in high-impedance - protecting shared buses from contention or latch-up during initialization.