Lattice GAL22V10D-5LJ: Architecture, Features, and Key Applications

The Lattice GAL22V10D-5LJ stands as a classic and highly influential device in the history of programmable logic. As a member of the Generic Array Logic (GAL) family, it provided a powerful, erasable, and one-time programmable (OTP) alternative to rigid standard logic products and earlier programmable logic devices (PLDs). Its architecture, a refinement of the common PAL® structure, is centered around a programmable AND array feeding into fixed OR terms. The key differentiator for the GAL22V10D was its advanced output logic macrocell (OLMC). Each of its ten outputs is configured through a user-programmable macrocell, allowing for tremendous flexibility. These macrocells can be individually set to operate as combinatorial outputs or registered (clocked) outputs, and the output polarity (active-high or active-low) is also programmable.

The "22V10" designation is descriptive: 22 inputs and 10 outputs. The "-5LJ" suffix indicates a 5ns maximum propagation delay (tPD) and a leadless J-lead (PLCC) package. Key features that cemented its popularity include its high-speed 5ns performance, which was critical for timing-critical applications, and its CMOS-based low-power operation, making it suitable for a wide range of environments. Furthermore, its electrically erasable (E2CMOS) technology was a major advancement, allowing designers to reprogram the device countless times during development, drastically reducing design cycle time and cost compared to fuse-based OTP parts.

The applications for the GAL22V10D-5LJ were vast, serving as a fundamental building block in digital systems throughout the 1990s and early 2000s. A primary use case was glue logic integration, where it replaced numerous small- and medium-scale integration (SSI/MSI) ICs like gates, flip-flops, and decoders to reduce board space, component count, and cost. It was also extensively used for implementing state machines and complex combinatorial logic, serving as the control logic for larger systems. Additionally, it found purpose in address decoding for microprocessor and microcontroller systems, generating chip-select signals for memory and peripherals, and in bus interfacing and signal conditioning.

ICGOOODFIND: The Lattice GAL22V10D-5LJ was a cornerstone of digital design, prized for its reprogrammability, flexible output macrocells, and high speed, which made it an indispensable tool for logic integration and system control.

Keywords: Programmable Logic Device (PLD), Output Logic Macrocell (OLMC), Glue Logic, High-Speed Logic, E2CMOS Technology.