ISPLSI 3256A-70LQI

Complex Programmable Logic Devices Overview

The ispLSI 3256A-70LQI is a discontinued high-density in-system programmable logic device (PLD) manufactured by Lattice Semiconductor. It features 11,000 PLD gates, 384 registers, and 128 universal I/O pins within a 160-pin PQFP package. Built on E2CMOS technology, the device supports a maximum operating frequency of 77 MHz with a propagation delay of 15 ns. Key specifications include five dedicated clock input pins, TTL-compatible inputs and outputs, and non-volatile reprogrammability. The component supports 5V in-system programming via Lattice ISP or IEEE 1149.1 Boundary Scan protocols.

Complex Programmable Logic Devices Feature Summary

• High-density architecture with 11,000 PLD gates, 384 registers, and 128 I/O pins.
• Non-volatile E2CMOS technology enabling electrically erasable and reprogrammable logic.
• In-system programmability (ISP) supporting 5V operation via Lattice ISP or IEEE 1149.1 Boundary Scan.
• TTL-compatible inputs and outputs with programmable output slew rate control.

Complex Programmable Logic Devices Applications

• Programmable SCSI Controller implementation as described in Lattice applications notes.
• Complex glue logic integration for high-performance computer systems.
• Address decoding and state machine design utilizing wide input gating capabilities.

Complex Programmable Logic Devices Procurement Notes

All devices in the ispLSI 3256A family are officially discontinued per Product Change Notification #09-10. Verification of part authenticity is critical when sourcing from secondary markets, as original manufacturing has ceased. Designers should confirm that existing inventory matches the specific -70 speed grade and 160-pin PQFP package requirements before procurement.

Complex Programmable Logic Devices Selection Notes

The -70 suffix indicates a maximum operating frequency of 77 MHz and a propagation delay of 15 ns. The 'I' suffix denotes Industrial temperature range capability (-40°C to +85°C), while the absence of this suffix indicates Commercial range (0°C to +70°C). The 'Q' specifies the 160-pin PQFP package. Ensure designs account for the specific timing constraints associated with the 77 MHz performance tier.

Complex Programmable Logic Devices Part Context

This component belongs to the ispLSI 3256A family, which serves as an enhanced version of the earlier ispLSI 3256 series. It utilizes Twin Generic Logic Blocks (Twin GLBs) and an Output Routing Pool (ORP) architecture to provide complete interconnectivity between logic elements. The device is functionally compatible with JEDEC files but requires updated Boundary Scan Description Library (BSDL) models for test and programming support.

Complex Programmable Logic Devices Replacement Considerations

Public datasheets do not list direct cross-model substitutes. Designers requiring equivalent functionality should evaluate modern Lattice FPGA or CPLD families. Verify pinout compatibility and logic density requirements when migrating from this discontinued PLD to alternative technologies.

Complex Programmable Logic Devices FAQ

What is the maximum operating frequency for the ispLSI 3256A-70LQI?

The maximum operating frequency (fmax) for the -70 speed grade is 77 MHz.

How many registers are available in the ispLSI 3256A device?

The device contains a total of 384 registers distributed across its 32 Twin Generic Logic Blocks.

Does the ispLSI 3256A support boundary scan testing?

Yes, the device is 100% IEEE 1149.1 Boundary Scan compatible and supports mandatory instructions such as BYPASS, EXTEST, and SAMPLE.