Lattice LC4256V75F256B-10I: A Comprehensive Technical Overview of the CPLD

The Lattice LC4256V75F256B-10I is a high-performance, low-power Complex Programmable Logic Device (CPLD) from Lattice Semiconductor's mature ispMACH 4000V family. Engineered for a wide range of general-purpose logic integration applications, this device offers a robust combination of density, speed, and power efficiency, making it a versatile solution for bridging, interfacing, and control functions in communications, computing, industrial, and consumer systems.

At the core of this CPLD are 256 macrocells, organized in a flexible logic structure. These macrocells are grouped into Function Blocks, each containing 16 macrocells, which are interconnected by a high-speed Global Routing Pool (GRP). This architecture ensures predictable timing performance and efficient implementation of complex combinatorial and sequential logic. The device features 75 MHz maximum operating frequency, a key indicator of its ability to handle high-speed signal processing and data path management. The `-10I` speed grade denotes a pin-to-pin logic propagation delay of just 10ns, ensuring rapid response times in critical applications.

A significant advantage of the LC4256V is its ultra-low power consumption, a hallmark of the ispMACH 4000V family. Utilizing a 1.8V core voltage with 3.3V, 2.5V, or 1.8V I/O options, it dramatically reduces static and dynamic power dissipation compared to older 5V CPLD technologies. This makes it particularly suitable for portable and battery-operated equipment where power management is paramount.

The device boasts 256-ball Fine-Pitch Ball Grid Array (fpBGA) packaging, which provides a compact footprint (17x17mm) ideal for space-constrained PCB designs. This package offers 192 user I/O pins, providing ample connectivity for interfacing with processors, memory, ASSPs, and other peripheral components. The I/O pins support various single-ended standards (LVCMOS, LVTTL) and are hot-socketing capable, allowing for insertion and removal from a live board without causing disruption.

A cornerstone of its programmability is the advanced in-system programmability (isp) via the IEEE 1149.1 (JTAG) interface. This allows for rapid prototyping and easy field upgrades without removing the device from the circuit board, significantly streamlining the manufacturing and development process. The non-volatile E²CMOS technology used for configuration ensures that the design is instantly available upon power-up, with no external boot ROM required.

In application, the LC4256V-10I excels in functions such as bus bridging (e.g., PCI to ISA), address decoding, state machine control, and I/O expansion. Its deterministic timing model eliminates the configuration delays associated with FPGAs, providing instant-on operation crucial for system control and initialization tasks.

ICGOOODFIND: The Lattice LC4256V75F256B-10I stands as a highly reliable and efficient workhorse in the CPLD domain. Its optimal blend of medium-density logic, high-speed performance, and exceptionally low power consumption makes it an enduring choice for designers seeking a proven, cost-effective solution for system integration and glue logic. Its ease of use, live in-system programmability, and small form factor continue to secure its relevance in modern electronic design.

Keywords: CPLD, Low Power, ispMACH 4000V, In-System Programmability (ISP), High-Speed Logic.