Lattice GAL18V10B-20LJ: Architecture, Key Features, and Target Applications
The Lattice GAL18V10B-20LJ represents a specific implementation of a high-performance, low-power programmable logic device (PLD) from the Generic Array Logic (GAL) family. As a 20-pin, PLCC-packaged device with a maximum propagation delay of 20ns, it serves as a versatile building block for a wide range of digital logic applications, offering a reliable alternative to fixed-function TTL logic.
Architecture
The architecture of the GAL18V10B is centered around its programmable AND array and a fixed OR array, a structure typical of Simple Programmable Logic Devices (SPLDs). The "18V10" designation indicates it has 10 output logic macrocells (OLMCs) and can accept up to 18 inputs. Each macrocell is user-configurable, allowing individual outputs to be defined as either combinatorial or registered (clocked). A key architectural advantage is the programmable output polarity for each macrocell, enabling output signals to be either active-high or active-low. This simplifies logic design by efficiently implementing DeMorgan's Law in hardware. The device is based on Electrically Erasable CMOS (EECMOS) technology, which allows for high-speed operation, low power consumption, and the ability to be reprogrammed multiple times.
Key Features
High Performance: The `-20LJ` suffix denotes a maximum propagation delay of 20 nanoseconds, making it suitable for high-speed logic implementations.
Low Power Consumption: Built on CMOS technology, it consumes significantly less power than its bipolar (e.g., PAL) predecessors.
10 Fully Configurable Macrocells: Each output can be independently configured as a registered or combinatorial I/O, providing immense design flexibility.
UltraMOS® Advanced CMOS Technology: This ensures high reliability and low static power dissipation.
100% Tested/High Reliability: Lattice's manufacturing process ensures a low power-to-speed ratio and high quality.
Electrically Erasable Cells: The device can be reprogrammed and tested repeatedly, accelerating design development and prototyping cycles.
Target Applications
The GAL18V10B-20LJ is designed to replace multiple fixed-function TTL logic chips, reducing board space, component count, and system cost. Its primary target applications include:
Address Decoding: In microprocessor and microcontroller-based systems, it is ideal for generating chip-select and memory-mapped I/O control signals.
State Machine Control: It can implement simple finite state machines (FSMs) for controlling sequential logic operations.
Bus Interface Logic: Used for implementing glue logic, such as signal level translation, buffering, and protocol conversion between different parts of a system.
Digital Signal Conditioning: Functions like pulse shaping, synchronization, and simple data routing are easily implemented.
System Configuration and Control: It is perfect for integrating numerous discrete gates into a single chip to manage system initialization and mode control.
The Lattice GAL18V10B-20LJ stands as a classic and robust SPLD solution. Its blend of a flexible macrocell architecture, high-speed 20ns performance, and low-power CMOS technology makes it an enduring choice for designers seeking to consolidate logic, simplify board design, and enhance system reliability in a cost-effective package.
Keywords: Programmable Logic Device (PLD), Output Logic Macrocell (OLMC), Electrically Erasable CMOS (EECMOS), Propagation Delay, Glue Logic
