71256L45DB SRAM Memory IC - Equivalent & Substitute Parts

Part Overview

The 71256L45DB is a 256Kbit asynchronous SRAM memory integrated circuit manufactured by Renesas Electronics Corporation. This parallel interface memory device operates with a 45 nanosecond access time and is housed in a 28-pin CDIP package. The product is classified as obsolete, making identification of functionally equivalent substitute components essential for system maintenance, repair, and legacy equipment support. Substitute parts must maintain identical memory capacity, organization, packaging, and electrical specifications to ensure direct compatibility without circuit redesign.

Substiute Parts

71256L45DB

Renesas Electronics CorporationIn Stock: 10718271256L45DB Datasheet

Current PartRFQ

71256L70DB

Renesas Electronics CorporationIn Stock: 225271256L70DB Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 71256L45DB is determined by the following critical parameters:

Mandatory Matching Parameters:

• Memory Size: 256Kbit
• Memory Organization: 32K x 8
• Memory Format: SRAM (Asynchronous)
• Memory Interface: Parallel
• Package Type: 28-CDIP
• Voltage Supply Range: 4.5V ~ 5.5V
• Operating Temperature Range: -55°C ~ 125°C
• Mounting Type: Through Hole

Variable Parameter (Allows Substitution):

• Access Time / Write Cycle Time: May differ from 45 ns, provided the substitute part meets or exceeds the speed requirement of the original application

The 71256L70DB qualifies as a substitute because it maintains all mandatory parameters while operating at a slower access time of 70 nanoseconds. This slower speed is acceptable in applications where the original 45 ns timing is not a critical constraint, as the substitute provides backward compatibility with identical memory capacity, organization, and physical form factor.

Parameter Comparison

Engineering Selection Recommendations

Both the 71256L45DB and 71256L70DB are classified as obsolete products. Selection between these parts depends on application timing requirements:

71256L45DB Selection Criteria:

• Applications requiring 45 nanosecond access time performance
• Systems with timing-critical memory access specifications
• Limited availability due to obsolete status

71256L70DB Selection Criteria:

• Applications where 70 nanosecond access time is acceptable
• Systems not constrained by the faster 45 ns timing specification
• Greater inventory availability (2200 units in stock versus 107090 units for the main part)
• Suitable for non-time-critical memory operations within the same circuit architecture

Both parts maintain identical RoHS3 compliance and REACH unaffected status, ensuring regulatory compatibility. The through-hole 28-CDIP package enables direct socket replacement without PCB modification.

Frequently Asked Questions (FAQ)

Q: Can the 71256L70DB directly replace the 71256L45DB in any application?

A: Direct replacement is possible only in applications where the 70 nanosecond access time meets system timing requirements. If the original design specifies 45 nanosecond timing as a critical parameter, the slower substitute may cause functional failure. Circuit timing analysis is required to confirm compatibility.

Q: Are there any physical differences between these parts?

A: No. Both parts use identical 28-CDIP packaging with 0.600" (15.24mm) body dimensions and through-hole mounting. Pin-to-pin compatibility is guaranteed, enabling direct socket substitution.

Q: Do both parts have the same power supply requirements?

A: Yes. Both the 71256L45DB and 71256L70DB operate within the 4.5V to 5.5V supply voltage range and support the identical -55°C to 125°C operating temperature range.

Q: What is the significance of the access time difference?

A: Access time defines the maximum delay between address input and valid data output. The 71256L45DB provides faster data retrieval at 45 ns, while the 71256L70DB requires 70 ns. Applications with strict timing budgets may not tolerate the 25 nanosecond increase.

Q: Are both parts RoHS compliant?

A: Yes. Both the 71256L45DB and 71256L70DB are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory standards.

Q: Which part should be selected for new designs?

A: Both parts are obsolete and unsuitable for new designs. Modern SRAM alternatives with higher density, lower power consumption, and extended availability should be evaluated for new applications.