71256SA15PDGI Equivalent & Substitute Parts

Part Overview

The 71256SA15PDGI is a 256Kbit asynchronous SRAM manufactured by Renesas Electronics Corporation, organized as 32K x 8 with a 15 ns access time. This through-hole mounted memory IC operates across the industrial temperature range of -40°C to 85°C and is designed for parallel data interface applications requiring volatile memory storage.

This part is classified as obsolete. Locating equivalent or substitute components is necessary to support legacy system maintenance, board-level repairs, and production continuity for applications where this specific device was originally specified.

Key Parameters

Parameter	Value
Memory Type	Volatile SRAM
Memory Size	256Kbit
Memory Organization	32K x 8
Memory Interface	Parallel
Access Time	15 ns
Write Cycle Time	15 ns
Supply Voltage	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package	28-DIP

Substitute Part Grouping Explanation

Substitution of the 71256SA15PDGI is determined by strict equivalence across the following parameters:

Critical Compatibility Parameters:

Memory capacity: 256Kbit (32K x 8 organization)
Memory technology: Asynchronous SRAM
Interface type: Parallel
Supply voltage range: 4.5V ~ 5.5V
Package type: 28-DIP through-hole
Pin count and pinout: 28 pins

Performance Parameters:

Access time must be equal to or faster than 15 ns
Write cycle time must be equal to or faster than 15 ns

Environmental Parameters:

Operating temperature range must encompass or exceed -40°C ~ 85°C

The 71256SA12TPG meets all critical compatibility parameters and exceeds performance specifications with a 12 ns access time and write cycle time. However, its operating temperature range (0°C ~ 70°C) is narrower than the original part, which may restrict its use in applications requiring the full -40°C ~ 85°C range.

Parameter Comparison

Parameter	71256SA15PDGI (Original)	71256SA12TPG (Substitute)
Manufacturer	Renesas Electronics Corporation	IDT, Integrated Device Technology Inc
Memory Size	256Kbit	256Kbit
Memory Organization	32K x 8	32K x 8
Memory Type	Volatile SRAM	Volatile SRAM
Technology	SRAM - Asynchronous	SRAM - Asynchronous
Memory Interface	Parallel	Parallel
Access Time	15 ns	12 ns
Write Cycle Time	15 ns	12 ns
Supply Voltage	4.5V ~ 5.5V	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	0°C ~ 70°C
Mounting Type	Through Hole	Through Hole
Package / Case	28-DIP (0.600", 15.24mm)	28-DIP (0.300", 7.62mm)
Product Status	Obsolete	Active

Engineering Selection Recommendations

71256SA12TPG Substitution Criteria:

The 71256SA12TPG is an active product from IDT and serves as a functional substitute for the obsolete 71256SA15PDGI. Both devices share identical memory capacity, organization, interface type, and supply voltage specifications. The substitute offers improved performance with faster access and write cycle times (12 ns versus 15 ns).

Temperature Range Consideration:

The primary engineering constraint is the operating temperature range. The 71256SA12TPG operates from 0°C to 70°C, whereas the original part operates from -40°C to 85°C. Applications requiring operation below 0°C or above 70°C cannot use this substitute without additional thermal management or design modification.

Package Dimension Variance:

The 28-DIP package dimensions differ between the two parts (0.600" versus 0.300" body width). This dimensional difference may affect PCB layout compatibility, socket fit, and mechanical clearance. Physical verification is required before board-level substitution.

Product Status:

The 71256SA12TPG is an active product with current manufacturing and distribution support, providing supply chain continuity for legacy system maintenance and repair operations.

Frequently Asked Questions (FAQ)

Q: Can the 71256SA12TPG directly replace the 71256SA15PDGI in all applications?

A: Electrical and functional compatibility is confirmed for applications operating within 0°C to 70°C. Applications requiring the full -40°C to 85°C temperature range require alternative solutions. Physical package dimensions differ; PCB socket and mechanical clearance must be verified.

Q: What is the significance of the 12 ns versus 15 ns access time difference?

A: The 71256SA12TPG has faster access and write cycle times. In timing-critical applications, this faster performance is compatible with designs specified for 15 ns operation. The substitute will not introduce timing violations in circuits designed for the slower original part.

Q: Are the pin configurations identical between these two parts?

A: Both devices use 28-pin DIP packages with parallel interface architecture. Pin-to-pin compatibility is confirmed. However, physical package body dimensions differ, which may affect socket compatibility and PCB layout.

Q: What supply voltage range applies to both parts?

A: Both the 71256SA15PDGI and 71256SA12TPG operate across 4.5V to 5.5V supply voltage. No voltage regulation modifications are required for substitution within this range.

Q: Is the 71256SA12TPG suitable for industrial temperature applications?

A: The 71256SA12TPG operates from 0°C to 70°C, which covers commercial and light industrial temperature ranges. Applications requiring -40°C operation or temperatures above 70°C require alternative components or thermal management solutions.

Q: What is the memory organization of both parts?

A: Both devices are organized as 32K x 8 (32,768 words by 8 bits), providing 256Kbit total capacity. Memory addressing and data bus width are identical.

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