LC4256C-5FT256AI Equivalent & Substitute Parts

Part Overview

The LC4256C-5FT256AI is a Complex Programmable Logic Device (CPLD) from Lattice Semiconductor Corporation's ispMACH® 4000C series. This embedded integrated circuit features 256 macrocells with a maximum propagation delay of 5 nanoseconds and supports in-system programming. The device is classified as obsolete, making identification of suitable substitute components essential for ongoing system support, maintenance, and new design implementations where legacy compatibility is required.

Substiute Parts

LC4256C-5FT256AI

Lattice Semiconductor CorporationIn Stock: 1390LC4256C-5FT256AI Datasheet

Current PartRFQ

LC4256V-5FTN256AC

Lattice Semiconductor CorporationIn Stock: 1482LC4256V-5FTN256AC Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LC4256C-5FT256AI is determined by strict alignment of the following critical parameters:

Functional Equivalence Parameters:

• Macrocell count: 256 (must match)
• Logic elements/blocks: 16 (must match)
• I/O count: 128 (must match)
• Propagation delay: 5 ns maximum (must match)
• Programmable type: In System Programmable (must match)
• Package type: 256-FTBGA (17x17) (must match)

Allowable Variations:

• Voltage supply range may differ based on device series variant
• Operating temperature range may differ based on device grade
• Product status may transition from obsolete to active
• RoHS compliance status may improve
• Packaging format (tray vs. tube) may vary

The LC4256V-5FTN256AC from the ispMACH® 4000V series satisfies all functional equivalence parameters while representing an active product variant with improved compliance characteristics.

Parameter Comparison

Engineering Selection Recommendations

The LC4256V-5FTN256AC qualifies as a functional substitute for the LC4256C-5FT256AI based on matching core logic architecture, I/O configuration, and timing specifications. Selection between these variants depends on system-level requirements:

LC4256C-5FT256AI Selection Criteria:

• Legacy system maintenance requiring exact voltage supply range (1.65V ~ 1.95V)
• Extended operating temperature range requirement (-40°C ~ 105°C)
• Existing inventory or supply chain constraints

LC4256V-5FTN256AC Selection Criteria:

• New designs or system upgrades
• ROHS3 compliance requirement
• Standard industrial operating temperature range (0°C ~ 90°C) acceptable
• 3V ~ 3.6V supply voltage compatibility with system architecture
• Active product status ensuring ongoing manufacturer support and availability

Both devices share identical package geometry (256-FTBGA, 17x17), macrocell count (256), I/O configuration (128), and propagation delay specification (5 ns maximum), ensuring pin-compatible PCB layouts and equivalent functional performance within their respective operating parameters.

Frequently Asked Questions (FAQ)

Q: Can LC4256V-5FTN256AC be used as a direct replacement for LC4256C-5FT256AI?

A: Functional substitution is possible if system voltage supply and operating temperature ranges accommodate the LC4256V variant specifications (3V ~ 3.6V supply, 0°C ~ 90°C operating range). PCB layout compatibility is confirmed due to identical 256-FTBGA package geometry. Verification of power supply architecture and thermal environment is required before implementation.

Q: What are the key differences between these two parts?

A: The primary differences are voltage supply range, operating temperature range, product status, and RoHS compliance. The LC4256C operates at 1.65V ~ 1.95V with extended temperature range (-40°C ~ 105°C) and is obsolete. The LC4256V operates at 3V ~ 3.6V with standard temperature range (0°C ~ 90°C), is active, and ROHS3 compliant. Both share identical logic architecture, macrocell count, I/O configuration, and timing performance.

Q: Are the package dimensions identical?

A: Yes. Both devices use the 256-FTBGA (17x17) package with 256-LBGA case designation. Pin count, pitch, and footprint are identical, enabling direct PCB layout compatibility.

Q: What is the significance of the different voltage supply ranges?

A: The LC4256C operates at lower voltage (1.65V ~ 1.95V), typical of older CPLD designs. The LC4256V operates at standard 3V ~ 3.6V logic levels. System power supply architecture must support the selected device voltage range. Substitution requires confirmation that the target system can provide the appropriate supply voltage.

Q: Does the operating temperature range difference affect substitution?

A: The LC4256C supports extended temperature operation (-40°C ~ 105°C), while the LC4256V operates within standard industrial range (0°C ~ 90°C). Substitution is valid only if the application environment falls within the LC4256V operating range. Extended temperature applications require retention of the LC4256C or alternative solutions.

Q: What does "In System Programmable" mean for substitution purposes?

A: Both devices support in-system programming, meaning firmware updates can be performed without device removal from the PCB. This characteristic is identical between variants, ensuring equivalent programmability and field update capability.

Q: Is RoHS compliance a substitution factor?

A: RoHS compliance affects regulatory and supply chain considerations but does not impact electrical or functional compatibility. The LC4256V-5FTN256AC offers ROHS3 compliance, beneficial for new designs and regulated markets. The LC4256C non-compliance is acceptable for legacy system maintenance where regulatory requirements are already established.