Lattice Semiconductor ISPLSI1048C-70LQ: A Comprehensive Technical Overview of the High-Density CPLD

In the realm of digital logic design, Complex Programmable Logic Devices (CPLDs) serve as a critical bridge between the inflexibility of simple PLDs and the high capacity of FPGAs. The Lattice Semiconductor ISPLSI1048C-70LQ stands as a quintessential example of a high-density, in-system programmable CPLD from a pioneering family. This device encapsulates a powerful blend of density, performance, and flexibility, making it a historically significant and still relevant component for a wide array of control logic and glue logic applications.

Architectural Foundation: The High-Density ispLSI Family

The ISPLSI1048C belongs to Lattice's high-performance ispLSI 1000E family. This family is renowned for its innovative Generic Logic Block (GLB) architecture, which forms the core of its programmability. The 1048C variant is specifically characterized by its high gate count, featuring an equivalent of 8,000 PLD gates. This density allows it to integrate numerous discrete logic ICs onto a single chip, reducing board space, component count, and overall system cost.

The architecture is organized around a global routing pool (GRP), a central interconnect resource that provides a predictable, deterministic timing path between all internal elements. This is a key differentiator from FPGAs, as it eliminates the routing uncertainties that can lead to timing delays, making CPLDs like the 1048C ideal for state machines and control applications requiring consistent performance.

Key Technical Specifications and Features

High Logic Density: With its 8,000-gate capacity, the device can implement complex logic functions, state machines, and address decoders.

In-System Programmability (ISP): The namesake "isp" feature is a cornerstone of its design. Utilizing an IEEE 1149.1 (JTAG) interface, the device can be reprogrammed while soldered onto the circuit board. This drastically simplifies prototyping, field upgrades, and design iterations.

Performance: The "-70LQ" suffix denotes a maximum pin-to-pin delay of 7.5 ns, enabling operation at system frequencies well above 100 MHz. This high speed is crucial for modern, fast-paced digital systems.

I/O Capabilities: The device is packaged in a 100-pin Low-profile Quad Flat Pack (LQFP), offering 64 dedicated I/O pins. These pins are organized into four I/O banks, providing flexible interface capabilities with TTL-compatible voltages (3.3V).

Non-Volatile E²CMOS Technology: The configuration is stored in E²CMOS (Electrically Erasable CMOS) cells. This technology makes the device instant-on upon power-up, as it does not require an external boot configuration memory, unlike SRAM-based FPGAs.

Target Applications

The combination of deterministic timing, non-volatile storage, and high density made the ISPLSI1048C-70LQ a preferred choice for a multitude of applications, including:

System Control Logic: Acting as a "glue logic" device to interconnect and manage data flow between microprocessors, ASICs, and memory.

Bus Interface and Protocol Bridging: Implementing interfaces for PCI, CPU buses, or custom serial/parallel protocols.

Address Decoding: Efficiently generating chip-select signals for memory-mapped systems.

DMA Control and State Machine Design: Its fast, predictable timing is perfect for designing complex state machines.

Conclusion and Design Considerations

The Lattice Semiconductor ISPLSI1048C-70LQ represents a high-water mark for high-density CPLD technology. Its robust architecture, featuring a global routing pool and generic logic blocks, delivers the deterministic timing essential for critical control-path applications. While newer, more power-efficient families have since emerged, the 1048C remains a testament to a design philosophy that prioritizes reliability, integration, and in-system reconfigurability.

ICGOODFIND: The Lattice ispLSI1048C-70LQ is a high-density, in-system programmable CPLD renowned for its 8,000-gate logic capacity and deterministic pin-to-pin delays. Its non-volatile, instant-on nature and JTAG programmability made it an industry workhorse for integrating complex control logic and simplifying board design.

Keywords: CPLD, In-System Programmability (ISP), High-Density Logic, Deterministic Timing, Generic Logic Block (GLB)