Lattice LC4256ZC-75TN100I: A Comprehensive Technical Overview of the CPLD

In the realm of digital logic design, Complex Programmable Logic Devices (CPLDs) remain a cornerstone for "glue logic," system configuration, and control applications. The Lattice LC4256ZC-75TN100I represents a specific and capable implementation within Lattice Semiconductor's proven ispMACH 4000ZE family. This article provides a detailed technical examination of this component, highlighting its architecture, key features, and target applications.

At its core, the LC4256ZC is a high-performance, 3.3V CPLD. The "4256" in its name denotes its macrocell count, signifying a substantial logic capacity with 256 macrocells organized into multiple Logic Blocks. This architecture provides a predictable, deterministic timing model crucial for state machine and control-oriented designs. The device is built on a non-volatile, in-system programmable (ISP) E²CMOS technology. This foundation allows the device to be reprogrammed indefinitely while retaining its configuration upon power-down, a critical feature for prototyping and field updates.

The device's performance is highlighted by its -75 speed grade, indicating a pin-to-pin logic propagation delay as low as 7.5ns. This high speed enables its use in bus interfacing, address decoding, and other timing-critical system functions. The "ZC" package code and "TN100I" suffix specify a 100-pin Thin Quad Flat Pack (TQFP) with a commercial (0°C to +70°C) operating temperature range. This package offers a balance between physical size and I/O availability, featuring 80 user I/O pins. These pins support various I/O standards, including LVCMOS 3.3V/2.5V/1.8V and LVTTL, ensuring flexible interfacing with other system components.

A significant strength of the ispMACH 4000ZE family is its low power consumption. The LC4256ZC-75TN100I utilizes a 1.8V core voltage with 3.3V I/O buffers, resulting in exceptionally low standby and dynamic power consumption. This makes it an ideal choice for portable, battery-operated, and power-sensitive electronics. Furthermore, the device features advanced system integrity support, including 5V tolerant I/Os and hot-socketing capability, allowing it to be inserted or removed from a live circuit without causing disruption.

The integration of a dedicated JTAG (IEEE 1532) interface simplifies the design and testing process. This interface facilitates not only programming and configuration but also sophisticated boundary scan testing, enabling complex system-level tests for board connectivity and manufacturing defects.

Typical applications for the Lattice LC4256ZC-75TN100I are diverse. It is perfectly suited for:

Address decoding and bus interfacing in microprocessor and microcontroller-based systems.

System configuration and control for FPGAs, ASICs, and other peripherals.

Data path control and bridging between interfaces of different voltages or protocols.

Function integration, consolidating numerous discrete logic ICs into a single, reliable, and reprogrammable component.

ICGOODFIND: The Lattice LC4256ZC-75TN100I is a robust and flexible CPLD solution that excels in deterministic timing, low-power operation, and high integration. Its combination of 256 macrocells, 80 I/Os, and 7.5ns performance makes it a powerful tool for solving a wide array of digital logic challenges in control-intensive applications, particularly where low power and field-upgradability are paramount.

Keywords: CPLD, Lattice Semiconductor, ispMACH 4000ZE, In-System Programmable (ISP), Low-Power.