Lattice GAL16V8D-15LD/883: A Comprehensive Technical Overview and Application Guide

The Lattice GAL16V8D-15LD/883 represents a cornerstone of programmable logic design, a device that has proven its reliability and versatility across decades, particularly in demanding military and aerospace applications. As a member of the renowned Generic Array Logic (GAL) family, this device combines the flexibility of reprogrammability with the robustness required for extended lifecycles and harsh environments. This article provides a detailed examination of its architecture, key specifications, and practical application guidance.

Architectural Overview

The GAL16V8 is an electrically erasable, CMOS-based programmable logic device (PLD). Its architecture is defined by a programmable "AND" array feeding into fixed "OR" arrays and sophisticated output logic macrocells (OLMCs). The "16" in its name refers to the number of inputs, while the "V8" denotes the eight available outputs, each configurable through its macrocell. The OLMCs are the heart of its flexibility, allowing each output pin to be individually programmed as a combinatorial or registered output. This configurability enables the implementation of a vast array of logic functions, including state machines, decoders, and complex glue logic.

Decoding the Part Number: GAL16V8D-15LD/883

GAL16V8: The base family and model.

D: Indicates the specific die revision or variant.

-15: This is a critical speed grade. It signifies a maximum propagation delay (tPD) of 15 nanoseconds, making it suitable for clock speeds up to approximately 66 MHz.

LD: Denotes the package type; in this case, a 20-pin Ceramic Leadless Chip Carrier (LCC).

/883: This suffix is paramount. It certifies that the device is manufactured, screened, and tested in full compliance with the stringent MIL-PRF-38535 Class V standard. This ensures high reliability, extended temperature range operation (typically -55°C to +125°C), and rigorous quality control for military and aerospace applications.

Key Features and Specifications

The GAL16V8D-15LD/883 is characterized by several robust features:

High Reliability /883 Screening: Qualified for space-level and military applications.

100% Programmability and Testability: Can be erased and reprogrammed, facilitating design iteration and bug fixes.

Eight Output Logic Macrocells: Each can be configured for a specific output function (registered, combinatorial, input-only).

Low Power Consumption: Advanced CMOS technology ensures low standby and active current.

Electrostatic Discharge (ESD) Protection: Enhanced protection on all pins.

Application Guide and Design Considerations

1. Replacing Standard Logic: Its most classic use case is consolidating multiple TTL (e.g., 74-series) ICs into a single chip, reducing board space, part count, and power consumption while improving system reliability.

2. Implementing State Machines: The registered output mode allows for the creation of simple to moderately complex state machines directly within the PLD.

3. Address Decoding: It is exceptionally well-suited for generating chip select (CS) and wait-state signals in microprocessor systems.

4. Interface Logic: Acts as a "glue logic" device, translating between different voltage levels or timing protocols of various system components.

Design and Programming Process:

The design flow involves writing logic equations or creating a schematic using a Hardware Description Language (HDL) like CUPL or Abel. A compiler then translates this into a JEDEC file, which is used to program the physical device using a dedicated programmer. It is crucial to simulate the design thoroughly before programming to verify timing and functionality.

ICGOOODFIND

The Lattice GAL16V8D-15LD/883 remains a highly relevant and trusted solution for engineers designing for high-reliability sectors. Its blend of proven architecture, military-grade /883 certification, and exceptional design flexibility makes it an indispensable component for legacy system support and new designs where utmost reliability is non-negotiable. While newer CPLDs and FPGAs offer greater density, the GAL16V8's simplicity, low power, and radiation-hardened potential ensure its enduring legacy.

Keywords:

1. Programmable Logic Device (PLD)

2. Military Grade (/883)

3. Output Logic Macrocell (OLMC)

4. Propagation Delay (tPD)

5. Glue Logic