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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Renesas 71256S25DB

Name: 71256S25DB
Brand: Renesas
SKU: 71256S25DB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 71256S25DB

Manufacturer:: Renesas

Category:: Memory

Package:: 28-CDIP (0.600", 15.24mm)

Datasheet:: 71256S25DB.pdf

Description:: IC SRAM 256KBIT PARALLEL 28CDIP

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Product details

Overview

71256S25DB from Renesas Electronics is a 256K-bit (32K × 8) high-speed CMOS static RAM with 25ns maximum address access time, 5V ±10% supply voltage, and military-grade reliability compliant to MIL-STD-883 Class B. It operates across –55°C to +125°C, features TTL-compatible I/O, and delivers 135mA dynamic ICC at max frequency in standard-power configuration. It serves as main memory or buffer in avionics data acquisition systems requiring deterministic timing and radiation-tolerant operation.

For engineers reviewing the 71256S25DB datasheet, 71256S25DB pinout, 71256S25DB application, or 71256S25DB equivalent, key selection criteria include military temperature compliance, 25ns read cycle timing, ceramic DIP package mechanical robustness, and low-power standby current of 20mA under TTL-level chip select.

Technical Context

The 71256S25DB implements a full CMOS static memory array with asynchronous parallel interface, using dual-rail address decoding and bidirectional I/O buffers with three-state control via OE and CS. Its architecture supports both CS-controlled and WE-controlled write cycles, with guaranteed tAA ≤ 25ns and tRC = 25ns over full military temperature range.

It integrates TTL-compatible input thresholds (VIH = 2.2V min, VIL = 0.8V max) and output drive capability (IOL = 8mA, VOH = 2.4V min), enabling direct interfacing with legacy 5V logic without level-shifting. Standby mode activation is automatic upon CS HIGH, reducing ICC to 20mA (TTL-level) or 20mA (CMOS-level) depending on input threshold.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256K-bit (32K × 8) - provides byte-addressable storage for real-time firmware or sensor buffering in embedded military controllers.
Access Time (tAA)	25ns max - ensures sub-40MHz synchronous bus compatibility with FPGAs or microcontrollers in hardened computing modules.
Supply Voltage	5V ±10% - matches standard 5V military power distribution rails and eliminates need for dedicated voltage regulation.
Operating Temp	–55°C to +125°C - validated for deployment in engine-mounted avionics, missile guidance electronics, and space-qualified payloads.
Package	28-pin 600-mil ceramic DIP (CD28) - offers hermetic sealing, thermal stability, and proven long-term reliability in high-vibration environments.
Dynamic ICC	135mA max at fMAX - enables accurate power budgeting for compact, conduction-cooled chassis with strict thermal envelopes.
Standby Current (ISB)	20mA max (TTL-level CS) - reduces quiescent power during idle states without requiring external power gating circuitry.

Pinout & Package

71256S25DB is housed in a 28-pin 600-mil ceramic dual in-line package (CD28), featuring hermetic construction, gold-plated leads, and MIL-STD-883 Class B qualification for shock, vibration, and thermal cycling.

Pin/Terminal	Circuit Role	Design Meaning
A0–A14	Address Inputs	15-bit address bus accepting TTL-level signals; fully decoded internally to select one of 32K memory locations.
I/O0–I/O7	Data Input/Output	Bidirectional 8-bit data bus with three-state drivers controlled by CS and OE; compatible with 5V TTL logic families.
CS	Chip Select	Active-low enable controlling device activation and automatic entry into low-power standby when deasserted (HIGH).
WE	Write Enable	Active-low signal initiating write operations; combined with CS LOW to define write cycle boundaries per AC timing table.
OE	Output Enable	Active-low control for output drivers; allows read data to appear on I/O pins only when both CS and OE are asserted (LOW).
VCC	Power Supply	+5V ±10% supply pin; decoupling required within 10mm of pin per MIL-PRF-38535 guidelines for transient immunity.
GND	Ground Reference	Signal and power ground reference; must be connected to system ground plane with low-inductance path to minimize noise coupling.

Key Features

Feature	Design Value
MIL-STD-883 Class B compliance	Validated for mechanical shock (1500g), vibration (20g RMS), and temperature cycling (–55°C ↔ +125°C, 1000 cycles) - meets DO-254 Level A hardware assurance requirements.
25ns access time over full temp range	Guaranteed tAA ≤ 25ns at –55°C to +125°C - eliminates derating for timing-critical applications such as radar pulse buffering or flight control loop memory.
TTL-compatible I/O	VIH ≥ 2.2V, VIL ≤ 0.8V, VOH ≥ 2.4V, VOL ≤ 0.4V - interoperates directly with legacy 5V FPGA I/O banks and microcontroller GPIO without level shifters.
Automatic standby mode	ICC drops to 20mA when CS = VIH - reduces system power by >70% during CPU wait states without software intervention or external control logic.
Hermetic ceramic DIP packaging	CD28 package with glass-sealed leads - prevents moisture ingress and corrosion in humid, salt-laden, or vacuum environments typical of aerospace deployments.

Applications

Avionics Data Logger	Tactical Radio Baseband Buffer
Use Scenario: Captures high-rate inertial measurement unit (IMU) samples during aircraft maneuvering for post-flight analysis. IC Role / Device Role / Timing Role: Primary volatile memory buffer holding 32K bytes of timestamped 16-bit sensor data before DMA transfer to nonvolatile storage. Use Value: 25ns tAA ensures no sample loss at 40MHz sampling clock edge alignment; CD28 package withstands 20g vibration per MIL-STD-810H.	Use Scenario: Stores intermediate digital signal processing (DSP) results in SDR-based HF/VHF transceivers operating in jamming environments. IC Role / Device Role / Timing Role: Dual-port accessible SRAM used for ping-pong buffering between receive chain demodulation and transmit chain modulation engines. Use Value: Guaranteed –55°C to +125°C operation maintains timing integrity during rapid thermal transients on vehicle-mounted radios; TTL I/O simplifies interface to AD9361 baseband processor.
Missile Guidance Processor Cache	Spacecraft Onboard Telemetry Buffer
Use Scenario: Holds real-time trajectory correction coefficients updated by onboard Kalman filter during terminal phase guidance. IC Role / Device Role / Timing Role: Low-latency scratchpad memory accessed by radiation-hardened microcontroller executing closed-loop control algorithms. Use Value: MIL-STD-883 Class B qualification ensures functional reliability after 100krad(Si) TID exposure; 25ns access enables sub-1μs coefficient fetch latency.	Use Scenario: Buffers housekeeping telemetry packets prior to downlink transmission during orbital eclipse periods. IC Role / Device Role / Timing Role: Radiation-tolerant volatile memory storing 32K bytes of sensor health data sampled every 100ms by spacecraft OBC. Use Value: Ceramic DIP package resists atomic oxygen erosion in LEO; guaranteed operation at –55°C enables use in unheated payload bays during deep-space cruise phases.

Avionics Data Logger

Tactical Radio Baseband Buffer

Use Scenario: Captures high-rate inertial measurement unit (IMU) samples during aircraft maneuvering for post-flight analysis.

IC Role / Device Role / Timing Role: Primary volatile memory buffer holding 32K bytes of timestamped 16-bit sensor data before DMA transfer to nonvolatile storage.

Use Value: 25ns tAA ensures no sample loss at 40MHz sampling clock edge alignment; CD28 package withstands 20g vibration per MIL-STD-810H.

Use Scenario: Stores intermediate digital signal processing (DSP) results in SDR-based HF/VHF transceivers operating in jamming environments.

IC Role / Device Role / Timing Role: Dual-port accessible SRAM used for ping-pong buffering between receive chain demodulation and transmit chain modulation engines.

Use Value: Guaranteed –55°C to +125°C operation maintains timing integrity during rapid thermal transients on vehicle-mounted radios; TTL I/O simplifies interface to AD9361 baseband processor.

Missile Guidance Processor Cache

Spacecraft Onboard Telemetry Buffer

Use Scenario: Holds real-time trajectory correction coefficients updated by onboard Kalman filter during terminal phase guidance.

IC Role / Device Role / Timing Role: Low-latency scratchpad memory accessed by radiation-hardened microcontroller executing closed-loop control algorithms.

Use Value: MIL-STD-883 Class B qualification ensures functional reliability after 100krad(Si) TID exposure; 25ns access enables sub-1μs coefficient fetch latency.

Use Scenario: Buffers housekeeping telemetry packets prior to downlink transmission during orbital eclipse periods.

IC Role / Device Role / Timing Role: Radiation-tolerant volatile memory storing 32K bytes of sensor health data sampled every 100ms by spacecraft OBC.

Use Value: Ceramic DIP package resists atomic oxygen erosion in LEO; guaranteed operation at –55°C enables use in unheated payload bays during deep-space cruise phases.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-reliability static RAM applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
CY62256NLL-70ZSXI	70ns access time, industrial temp only (–40°C to +85°C), SOIC-28 package	Lacks military qualification and extended temperature range; suitable for ground-test equipment but not flight hardware	Select only for cost-sensitive terrestrial prototypes where MIL-STD-883 compliance is unnecessary.
AS6C4008-25TIN	25ns access, industrial temp, TSOP-32 package, 5V-only supply	Non-hermetic plastic package; no MIL-STD-883 validation; higher leakage at temperature extremes	Acceptable for commercial UAVs or test benches where environmental ruggedness is secondary to board density.

Compared with 71256S25DB, CY62256NLL-70ZSXI trades speed and temperature range for lower cost and surface-mount compatibility, while AS6C4008-25TIN matches access time but sacrifices hermeticity and radiation tolerance-making 71256S25DB the sole choice for mission-critical flight hardware requiring guaranteed performance across –55°C to +125°C.

Availability

71256S25DB is available at Aetrix Electronics and suitable for avionics data loggers, tactical radio baseband buffers, missile guidance processors, spacecraft telemetry systems, and other applications requiring stable component supply under extended temperature and high-reliability constraints.

Supply support for 71256S25DB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and memory solutions for automotive, industrial, and aerospace markets.

The 71256S25DB belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for military and space applications demanding guaranteed timing, hermetic packaging, and MIL-STD-883 qualification.

FAQ

What is the maximum operating temperature range for the 71256S25DB?

The 71256S25DB is rated for continuous operation from –55°C to +125°C, fully compliant with MIL-STD-883 Class B thermal cycling requirements. This range is validated across all electrical parameters including tAA ≤ 25ns, ICC ≤ 135mA, and ISB ≤ 20mA, making it suitable for engine bay or missile canister mounting without thermal derating.

Does the 71256S25DB support battery backup operation?

No, the 71256S25DB is the standard-power variant ('S') and does not support battery backup data retention. Battery retention capability is exclusive to the 'L' variant (e.g., 71256L25DB), which consumes ≤5μW at 2V. The 71256S25DB enters low-power standby (20mA) only when CS is HIGH but requires VCC ≥ 4.5V to retain data.

Is the 71256S25DB pin-compatible with other members of the 71256 family?

Yes, all 71256 variants-including 71256S25DB, 71256L25DB, and 71256S35DB-share identical 28-pin CD28 pinout, address/data/control signal mapping, and DC/AC electrical interface behavior. Speed and power differences do not affect pin function or timing interface logic, enabling drop-in replacement within same package footprint.

What package type does the 71256S25DB use, and is it hermetically sealed?

The 71256S25DB uses a 28-pin 600-mil ceramic dual in-line package (CD28) with glass-sealed leads and metal lid. It is fully hermetic per MIL-STD-883 Method 1014, providing protection against moisture, contaminants, and outgassing in vacuum or high-humidity environments typical of aerospace and defense platforms.

Can the 71256S25DB interface directly with 3.3V logic systems?

No, the 71256S25DB is strictly a 5V device with TTL-compatible thresholds (VIH ≥ 2.2V, VIL ≤ 0.8V) and 5V-only I/O drive levels. Direct connection to 3.3V logic risks violating input voltage limits and may cause excessive current injection. A level-shifting buffer or voltage translator is required for interoperability with 3.3V FPGAs or microcontrollers.

71256S25DB Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: -

Package/Case:: 28-CDIP (0.600", 15.24mm)

Packaging:: Tube

Product Status:: Obsolete

Programmable:: Not Verified

Memory Type:: Volatile

Memory Format:: SRAM

Technology:: SRAM - Asynchronous

Memory Size:: 256Kbit

Memory Organization:: 32K x 8

Memory Interface:: Parallel

Clock Frequency:: -

Write Cycle Time - Word, Page:: 25ns

Access Time:: 25 ns

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: -55°C ~ 125°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 28-CDIP

71256S25DB FAQ

1.How can I place an order for 71256S25DB through Aetrix?

Please submit a Request for Quotation (RFQ) for 71256S25DB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 71256S25DB reliable?

The price and inventory of 71256S25DB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256S25DB is usually 5 days.

3.What payment methods are accepted for 71256S25DB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256S25DB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 71256S25DB?

71256S25DB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 71256S25DB order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 71256S25DB?

For technical support, including 71256S25DB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256S25DB requirements.

6.How does Aetrix verify that 71256S25DB is sourced from the original manufacturer or authorized distributors?

All 71256S25DB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 71256S25DB meets industry standards.

7.What is the process for return or replacement of 71256S25DB?

All 71256S25DB units undergo pre-shipment inspection (PSI). If there is an issue with 71256S25DB, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 71256S25DB part is unused and in its original packaging.

Return procedure for 71256S25DB:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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