Equivalent & Substitute Parts for 71256S55DB

Part Overview

The 71256S55DB is a 256Kbit asynchronous SRAM manufactured by Renesas Electronics Corporation in a 28-CDIP package. This volatile memory IC features parallel interface architecture with 32K x 8 memory organization and 55 ns access time. The part is classified as obsolete, making substitute components necessary for ongoing system support and new design implementations. The primary reason for identifying alternatives is the discontinued product status, which limits availability for production and maintenance applications.

Substiute Parts

71256S55DB

Renesas Electronics CorporationIn Stock: 113571256S55DB Datasheet

Current PartRFQ

71256S100DB

Renesas Electronics CorporationIn Stock: 118071256S100DB Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 71256S55DB is determined by strict equivalence across the following critical parameters:

• Memory capacity: 256Kbit
• Memory organization: 32K x 8 configuration
• Memory type: Volatile SRAM
• Technology: Asynchronous SRAM
• Interface: Parallel
• Package: 28-CDIP form factor
• Voltage supply: 4.5V ~ 5.5V range
• Operating temperature: -55°C ~ 125°C range
• Mounting: Through Hole

The 71256S100DB qualifies as a substitute based on identical memory specifications, package configuration, voltage requirements, and temperature range. The primary difference is access time and write cycle time specification (100 ns versus 55 ns), which represents a relaxed timing requirement suitable for applications with less stringent speed demands.

Parameter Comparison

Engineering Selection Recommendations

The 71256S100DB is the designated substitute for the obsolete 71256S55DB. Selection of this alternative is based on the following engineering criteria:

Product Status: The 71256S100DB maintains active product status with Renesas Electronics Corporation, ensuring continued availability and supply chain reliability compared to the discontinued 71256S55DB.

Compliance Equivalence: Both parts share identical RoHS non-compliance status, MSL rating of 1 (Unlimited), and REACH unaffected classification, ensuring regulatory consistency in system design.

Functional Compatibility: The substitute maintains full electrical and mechanical compatibility through identical memory capacity, organization, interface type, package configuration, voltage supply range, and operating temperature specifications.

Timing Consideration: The 71256S100DB operates with 100 ns access and write cycle times compared to the 55 ns specification of the main part. This represents a timing relaxation that is acceptable for applications where the original 55 ns specification was not a critical design constraint.

Frequently Asked Questions (FAQ)

Q: Can the 71256S100DB directly replace the 71256S55DB in existing designs?

A: Direct replacement is possible from a physical and electrical standpoint. The 28-CDIP package, pinout, voltage supply range, and operating temperature specifications are identical. However, the 100 ns access time must be evaluated against system timing requirements. If the original design operated with 55 ns margins, timing analysis is necessary to confirm compatibility.

Q: What is the primary difference between these two parts?

A: The primary difference is access time and write cycle time. The 71256S55DB specifies 55 ns performance, while the 71256S100DB specifies 100 ns. Both parts are identical in memory capacity (256Kbit), organization (32K x 8), package type (28-CDIP), and electrical specifications (4.5V ~ 5.5V supply, -55°C ~ 125°C operating range).

Q: Why is the 71256S55DB classified as obsolete?

A: The 71256S55DB is listed as obsolete by Renesas Electronics Corporation, indicating discontinued manufacturing and limited availability. The 71256S100DB remains in active production status, providing a viable alternative for new designs and system maintenance.

Q: Are there any compliance differences between the substitute and the original part?

A: No. Both parts share identical RoHS non-compliance status, MSL rating of 1 (Unlimited), and REACH unaffected classification. Regulatory compliance posture is equivalent.

Q: What package considerations apply to this substitution?

A: Both parts use the 28-CDIP (0.600", 15.24mm) through-hole package. Physical dimensions, pin spacing, and mounting requirements are identical, allowing direct PCB compatibility without layout modifications.