LC4256B-75FT256AI Equivalent & Substitute Parts

Part Overview

The LC4256B-75FT256AI is a Complex Programmable Logic Device (CPLD) from Lattice Semiconductor's ispMACH® 4000B series, featuring 256 macrocells and 128 I/O pins in a 256-FTBGA package. This device is classified as obsolete, which necessitates identification of functionally equivalent alternatives for new designs and ongoing production requirements. The part operates with an internal voltage supply of 2.3V to 2.7V and delivers a maximum propagation delay of 7.5 nanoseconds.

Substiute Parts

LC4256B-75FT256AI

Lattice Semiconductor CorporationIn Stock: 1178LC4256B-75FT256AI Datasheet

Current PartRFQ

LC4256V-75FTN256AC

Lattice SemiconductorIn Stock: 743LC4256V-75FTN256AC Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LC4256B-75FT256AI is determined by strict equivalence in the following electrical and mechanical parameters:

• Macrocell Count: 256 macrocells (functional logic capacity)
• I/O Pin Count: 128 I/O pins (interface capability)
• Propagation Delay: 7.5 ns maximum (timing performance)
• Package Type: 256-FTBGA (17x17) (physical and electrical compatibility)
• Programmable Type: In System Programmable (programming methodology)
• Mounting Type: Surface Mount (assembly compatibility)

The LC4256V-75FTN256AC qualifies as a manufacturer-recommended substitute based on matching macrocell count, I/O configuration, propagation delay, package footprint, and programmable characteristics. Voltage supply range and operating temperature range differ between the main part and substitute, which must be evaluated against specific application requirements.

Parameter Comparison

Engineering Selection Recommendations

The LC4256V-75FTN256AC is the manufacturer-recommended substitute for the obsolete LC4256B-75FT256AI. Selection between these parts must account for the following factors:

Voltage Supply Compatibility: The LC4256B operates at 2.3V to 2.7V, while the LC4256V operates at 3V to 3.6V. Circuit power supply design must accommodate the voltage requirements of the selected device.

Operating Temperature Range: The LC4256B supports -40°C to 105°C, whereas the LC4256V supports 0°C to 90°C. Applications requiring extended low-temperature operation or high-temperature performance must verify compatibility with the LC4256V's narrower range.

Product Status and Availability: The LC4256B is obsolete with limited inventory (1119 pcs). The LC4256V is active with ongoing availability (660 pcs). New designs should prioritize the LC4256V to ensure long-term supply continuity.

Regulatory Compliance: The LC4256V is ROHS3 compliant, whereas the LC4256B is RoHS non-compliant. Applications subject to RoHS requirements must use the LC4256V.

Both parts share identical macrocell count, I/O configuration, propagation delay, package footprint, and programmable methodology, ensuring functional and physical compatibility at the component level.

Frequently Asked Questions (FAQ)

Q: Can the LC4256V-75FTN256AC directly replace the LC4256B-75FT256AI in existing designs?

A: Physical and functional replacement is possible due to matching macrocell count (256), I/O pin count (128), propagation delay (7.5 ns), and 256-FTBGA package. However, circuit power supply and operating temperature ranges must be verified for compatibility. The LC4256V requires 3V to 3.6V supply versus the LC4256B's 2.3V to 2.7V, and operates within 0°C to 90°C versus the LC4256B's -40°C to 105°C.

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

A: The primary electrical difference is the internal voltage supply range. The LC4256B operates at 2.3V to 2.7V (low-voltage variant), while the LC4256V operates at 3V to 3.6V (standard voltage variant). Both devices deliver identical 7.5 ns maximum propagation delay and support the same 256 macrocells and 128 I/O configuration.

Q: Are the package dimensions and pin assignments identical?

A: Yes. Both parts use the 256-FTBGA (17x17) package with identical physical dimensions and pin assignments. Surface mount assembly compatibility is maintained between the two parts.

Q: Why is the LC4256B classified as obsolete?

A: The LC4256B belongs to the ispMACH® 4000B series, which has reached end-of-life status. Lattice Semiconductor has transitioned production to the ispMACH® 4000V series, represented by the LC4256V-75FTN256AC, which offers improved compliance and active manufacturing support.

Q: Which part should be selected for new product designs?

A: The LC4256V-75FTN256AC should be selected for new designs. It is active, ROHS3 compliant, and supported by ongoing manufacturing. The LC4256B should be reserved for legacy system maintenance only.

Q: Are both parts In System Programmable?

A: Yes. Both the LC4256B-75FT256AI and LC4256V-75FTN256AC support In System Programmable (ISP) methodology, allowing field programming and reprogramming without removal from the circuit board.