Lattice GAL26CV12B-10LJ: A Comprehensive Technical Overview of the 10ns CPLD

The Lattice GAL26CV12B-10LJ represents a specific implementation of a high-performance Complex Programmable Logic Device (CPLD) from the venerable Generic Array Logic (GAL) family. This device is engineered for applications requiring rapid signal processing, sophisticated state machine control, and high-speed glue logic, all within a low-power, single-chip solution. Its 10ns maximum propagation delay (tPD) is a defining characteristic, positioning it as a solution for timing-critical systems of its era.

Architectural Foundation: The PAL Block Structure

At the core of the GAL26CV12B lies an architecture derived from Programmable Array Logic (PAL). The "26" in its designation refers to the number of inputs, while the "12" indicates the number of outputs. The device features a programmable AND array followed by a fixed OR array. Its key innovation over simpler PLDs is the inclusion of Output Logic Macro Cells (OLMCs). Each of the 12 outputs can be individually configured by the user for combinatorial or registered operation, and for active-high or active-low polarity. This flexibility allows a single device to replace numerous fixed-function TTL logic chips.

Key Technical Specifications and Features

High Speed: The -10 suffix denotes a maximum propagation delay of 10ns from any input to any output, enabling operation at clock frequencies exceeding 50 MHz.

CMOS Technology: Built on an electrically erasable CMOS (EECMOS) process, the device offers low standby power consumption and allows for full functional testing and reprogramming, facilitating rapid design iteration.

Programmable Outputs: The 12 OLMCs can be configured as dedicated inputs, dedicated combinatorial outputs, or registered outputs. Each output can be set for active-high or active-low operation.

100% Programmability and Testability: The EECMOS technology ensures the logic and interconnect are fully programmable. A security fuse can be programmed to prevent unauthorized copying of the design.

Package: The LJ suffix typically indicates a 28-pin Plastic Leaded Chip Carrier (PLCC) package, a common surface-mount package for through-hole and surface-mount assembly.

Application Domains

The combination of speed, deterministic timing, and logic integration made the GAL26CV12B-10LJ suitable for a wide range of applications, including:

Address Decoding: High-speed decoding in microprocessor and microcontroller-based systems.

State Machine Control: Implementing complex control logic for digital systems.

Bus Interface and Protocol Logic: Acting as an interface between components with different signaling standards.

Glue Logic Integration: Consolidating many discrete logic gates (e.g., from the 74-series) into a single, reliable chip, reducing board space and part count.

Design and Development

Development for the GAL26CV12B-10LJ was typically done using Hardware Description Languages (HDLs) like VHDL or Verilog, or schematic entry tools. The design was then processed by place-and-route software and ultimately translated into a JEDEC file. This file was used to program the device using a universal programmer, often requiring a specific PLCC socket adapter.

ICGOODFIND Summary

The Lattice GAL26CV12B-10LJ is a classic 10ns EECMOS CPLD that exemplifies the shift from fixed TTL logic to programmable solutions. Its defining feature is its high-speed performance, enabled by a deterministic PAL-based architecture. The device's primary strength lies in its configurable macro cells, which provide exceptional flexibility for logic implementation, making it an ideal choice for integrating glue logic, implementing state machines, and performing high-speed address decoding in legacy digital systems. While newer families like ispMACH® 4000 or FPGA solutions have largely superseded it, the GAL26CV12B remains a significant component in the history of programmable logic.

Keywords:

CPLD

10ns Propagation Delay

Output Logic Macro Cell (OLMC)

EECMOS

Programmable Logic