Lattice LC4256V-75TN176C: A Comprehensive Technical Overview of the CPLD

The Lattice LC4256V-75TN176C is a high-performance, high-density Complex Programmable Logic Device (CPLD) from Lattice Semiconductor's well-established ispMACH 4000V family. This device represents a significant solution for a wide range of applications requiring fast pin-to-pin speeds, in-system programmability, and robust logic integration. This overview delves into the key technical characteristics that define this component.

At its core, the LC4256V contains 256 macrocells, organized into four Function Blocks, providing a substantial amount of programmable logic for implementing complex state machines, glue logic, and bus interfacing. Each macrocell can be individually configured for registered or combinatorial operation, offering designers exceptional flexibility. The device is built on a 5.0V core voltage (VCC) with TTL-compatible inputs and outputs operating at 3.3V, making it suitable for mixed-voltage system environments common in its era.

A standout feature of this CPLD is its ultra-fast pin-to-pin logic delays of 7.5ns (max.), which is denoted by the "-75" in its part number. This high speed ensures that the device can handle critical timing paths and high-performance control tasks without becoming a system bottleneck. The architecture employs a programmable interconnect array (PIA) that routes signals between all function blocks, ensuring 100% routability and predictable timing performance across the entire device.

The package, a 176-pin Thin Quad Flat Pack (TQFP), offers a compact footprint while providing 133 user I/O pins. These I/Os are highly versatile, supporting various interface standards and featuring individual programmable output slew rate control to manage switching noise. The device is also renowned for its In-System Programmability (ISP) through the IEEE 1149.1 (JTAG) interface. This allows for rapid design iterations and field upgrades without removing the chip from the circuit board, drastically reducing development time and cost.

Power management is a key consideration, and the ispMACH 4000V architecture incorporates advanced features to keep power consumption low. The device utilizes a 3.3V power supply for I/O operations (VCCIO), reducing overall dynamic power. Furthermore, it offers a programmable power-down mode, enabling significant static power reduction in standby states.

In summary, the Lattice LC4256V-75TN176C is a powerful and flexible CPLD designed for high-speed, high-reliability logic consolidation. Its combination of dense macrocell count, predictable timing, and ISP makes it a classic choice for addressing complex digital design challenges in communications, computing, and industrial systems.

ICGOODFIND: The Lattice LC4256V-75TN176C CPLD is a robust and high-performance solution, ideal for system-level integration requiring fast response times and reliable re-programmability. Its balanced architecture of logic density, speed, and I/O count makes it a versatile component for legacy and modern 5V/3.3V system designs.

Keywords: CPLD, In-System Programmability (ISP), Macrocell, Pin-to-Pin Delay, JTAG