Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Renesas 71256S25TDB

Name: 71256S25TDB
Brand: Renesas
SKU: 71256S25TDB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: 71256S25TDB

Manufacturer:: Renesas

Category:: Memory

Package:: 28-CDIP (0.300", 7.62mm)

Datasheet:: 71256S25TDB.pdf

Description:: IC SRAM 256KBIT PARALLEL 28CDIP

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,458

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

71256S25TDB from Renesas is a 256K (32K × 8-bit) high-speed CMOS static RAM with 25ns maximum address access time, TTL-compatible I/O, and military-grade reliability compliant to MIL-STD-883 Class B. It operates across –55°C to +125°C, draws 135mA dynamic current at V_CC = 5.5V, and supports battery backup data retention at 2V for low-power hold mode. It serves as main memory or buffer in avionics, radar processors, and hardened embedded controllers.

For engineers reviewing the 71256S25TDB datasheet, 71256S25TDB pinout, 71256S25TDB application, or 71256S25TDB equivalent, key selection criteria include military temperature compliance, 28-pin ceramic DIP (300-mil) package, 25ns read cycle timing, standby current of 20mA (TTL-level CS), and direct TTL logic interface without level-shifting.

Technical Context

The 71256S25TDB implements a full CMOS SRAM architecture with asynchronous parallel interface, single 5V ±10% supply, and dual standby modes: TTL-level chip select (ISB = 20mA) and CMOS-level full standby (ISB1 = 20mA). Its address decoder drives a 262,144-bit memory array with on-chip I/O control enabling true bidirectional data flow via I/O0–I/O7.

Timing is governed by three independent control signals - CS, WE, and OE - supporting both CS-controlled and WE-controlled write cycles. Read operations require CS and OE low with WE high; write operations require CS and WE low, with OE irrelevant. Output enable/disable and chip select transitions define critical timing windows including tCLZ (5ns), tCHZ (11ns), and tOHZ (10ns).

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Organization	32K × 8-bit (262,144 bits), byte-wide parallel interface
Access Time (tAA)	25ns max - guarantees data valid within 25ns after address/CS stabilization for real-time signal buffering
Supply Voltage	4.5V–5.5V - compatible with standard 5V TTL/CMOS systems without regulation overhead
Operating Temperature	–55°C to +125°C - qualified for airborne, missile, and space-qualified platforms per MIL-STD-883 Class B
Dynamic Current (I_CC)	135mA max at f_MAX - defines worst-case power rail sizing and thermal design margin
Standby Current (I_SB)	20mA max with CS > V_IH - enables low-power sleep states during processor idle cycles
Input/Output Compatibility	TTL input thresholds (V_IL ≤ 0.8V, V_IH ≥ 2.2V); output drive ±8mA - interoperable with legacy 5V logic families

Pinout & Package

71256S25TDB is housed in a 28-pin ceramic dual in-line package (CDIP) with 300-mil body width (SD28), hermetically sealed for moisture resistance and long-term reliability in harsh environments.

Pin/Terminal	Circuit Role	Design Meaning
A0–A14	Address Inputs	15-bit address bus accepting 0–32,767 row/column selects; no internal latching - requires stable address before CS/WE assertion
I/O0–I/O7	Bidirectional Data Bus	8-bit multiplexed input/output port; direction controlled by WE/CS/OE state - eliminates need for external transceivers
CS	Chip Select	Active-low enable; forces device into standby when high - primary power-gating signal for system-level energy management
WE	Write Enable	Active-low write strobe; combined with CS low initiates write cycle - decouples write timing from address setup
OE	Output Enable	Active-low output gate; allows read data to appear on I/O pins only when asserted - prevents bus contention during writes
V_CC	Power Supply	+5V ±10% supply pin - must be decoupled locally with ≤100nF ceramic capacitor to sustain 135mA transient current
GND	Ground Reference	Signal and power return path - requires low-inductance connection to minimize noise coupling into memory array

Key Features

Feature	Design Value
MIL-STD-883 Class B qualification	Ensures operation under shock, vibration, temperature cycling, and radiation exposure required for defense electronics
25ns access time at military temperature range	Enables deterministic real-time response in radar pulse processing and flight control loops without wait states
Dual standby modes (TTL/CMOS CS levels)	Reduces system power by >90% during idle periods while maintaining fast wake-up latency (<10ns)
Hermetic 28-pin ceramic DIP (300-mil)	Provides long-term reliability in high-humidity, high-altitude, or corrosive environments where plastic packages fail
TTL-compatible I/O with 8mA drive	Interoperates directly with legacy FPGAs, microcontrollers, and ASICs without level translators or bus buffers

Applications

Avionics Flight Control Unit	Radar Signal Processing Buffer
Use Scenario: Real-time storage of inertial measurement unit (IMU) samples and actuator command history in fly-by-wire systems. IC Role / Device Role / Timing Role: High-reliability scratchpad memory holding 32K bytes of time-critical telemetry and control vectors. Use Value: 25ns access ensures sub-microsecond read/write latency for closed-loop servo updates at 1kHz+ rates.	Use Scenario: Temporary storage of digitized RF echo samples prior to FFT computation in pulse-Doppler radar front ends. IC Role / Device Role / Timing Role: Burst-mode data buffer synchronizing ADC output with DSP engine clock domain. Use Value: Military temperature rating and hermetic packaging prevent data corruption during rapid thermal transients in airborne radar bays.
Hardened Communication Transceiver	Tactical Data Link Interface
Use Scenario: Storing encrypted packet headers and payload fragments in SATCOM modems operating in jamming environments. IC Role / Device Role / Timing Role: Secure, non-volatile buffer retaining configuration and session keys during brownout events. Use Value: 2V data retention capability maintains cryptographic state for >100 hours on backup battery without refresh.	Use Scenario: Interfacing Link 16 terminals with mission computers requiring deterministic memory access under EMI stress. IC Role / Device Role / Timing Role: Timing-critical interface memory ensuring jitter-free data handoff between TACLANE and host processor. Use Value: MIL-STD-883 screening guarantees immunity to conducted transients and radiated susceptibility up to 200V/m.

Avionics Flight Control Unit

Radar Signal Processing Buffer

Use Scenario: Real-time storage of inertial measurement unit (IMU) samples and actuator command history in fly-by-wire systems.

IC Role / Device Role / Timing Role: High-reliability scratchpad memory holding 32K bytes of time-critical telemetry and control vectors.

Use Value: 25ns access ensures sub-microsecond read/write latency for closed-loop servo updates at 1kHz+ rates.

Use Scenario: Temporary storage of digitized RF echo samples prior to FFT computation in pulse-Doppler radar front ends.

IC Role / Device Role / Timing Role: Burst-mode data buffer synchronizing ADC output with DSP engine clock domain.

Use Value: Military temperature rating and hermetic packaging prevent data corruption during rapid thermal transients in airborne radar bays.

Hardened Communication Transceiver

Tactical Data Link Interface

Use Scenario: Storing encrypted packet headers and payload fragments in SATCOM modems operating in jamming environments.

IC Role / Device Role / Timing Role: Secure, non-volatile buffer retaining configuration and session keys during brownout events.

Use Value: 2V data retention capability maintains cryptographic state for >100 hours on backup battery without refresh.

Use Scenario: Interfacing Link 16 terminals with mission computers requiring deterministic memory access under EMI stress.

IC Role / Device Role / Timing Role: Timing-critical interface memory ensuring jitter-free data handoff between TACLANE and host processor.

Use Value: MIL-STD-883 screening guarantees immunity to conducted transients and radiated susceptibility up to 200V/m.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
CY62256BNLL-55ZSXI	55ns access, 32K×8, industrial temp only (–40°C to +85°C), SOIC-28 package	Lacks MIL-STD-883 qualification and hermetic sealing; unsuitable for flight-critical hardware	Select only for cost-sensitive ground-based test equipment where military specs are not mandated.
AS6C4008-55TIN	55ns access, 512K×8, commercial temp (0°C to +70°C), TSOP-32 package	Higher density but slower speed, no military qualification, plastic package limits humidity resistance	Use when board space is constrained and extended temperature operation is unnecessary.

Compared with CY62256BNLL-55ZSXI and AS6C4008-55TIN, the 71256S25TDB delivers faster 25ns timing, guaranteed operation down to –55°C, and MIL-STD-883 Class B reliability - making it the sole choice for deployed airborne, missile, and space systems requiring deterministic performance under environmental stress.

Availability

71256S25TDB is available at Aetrix Electronics and suitable for avionics, radar signal processing, and hardened communication systems requiring stable component supply across extended lifecycle programs.

Supply support for 71256S25TDB 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 71256S25TDB belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for military and aerospace applications demanding extended temperature operation, hermetic packaging, and MIL-STD-883 compliance.

FAQ

What is the maximum operating temperature range for the 71256S25TDB?

The 71256S25TDB is rated for operation from –55°C to +125°C and is fully qualified to MIL-STD-883 Class B for thermal cycling, mechanical shock, and vibration. This range is validated across all electrical parameters including 25ns access time, 135mA dynamic current, and 20mA standby current - making it suitable for engine-mounted or exoatmospheric deployments where ambient extremes exceed commercial or industrial grades.

Does the 71256S25TDB support battery backup data retention?

No - the 71256S25TDB is the standard-power variant ('S') and does not include battery backup data retention capability. That feature is exclusive to the 'L' version (e.g., 71256L25TDB), which consumes ≤3μA in full standby at 2V. The 71256S25TDB enters low-power standby (20mA) when CS is high but requires continuous 5V supply to retain data.

Is the 71256S25TDB pin-compatible with other 28-pin SRAMs like the 62256 series?

Yes - the 71256S25TDB uses the industry-standard 28-pin parallel SRAM pinout: A0–A14 on pins 1–12 and 23–24; I/O0–I/O7 on pins 13–20; CS on pin 21; WE on pin 22; OE on pin 23; V_CC on pin 24; GND on pin 12. This matches the 62256, HM62256, and AS6C2016 footprints, enabling drop-in replacement where speed and temperature requirements align.

What package type does the 71256S25TDB use, and is it RoHS-compliant?

The 71256S25TDB is supplied in a 28-pin ceramic DIP (CDIP) with 300-mil body width (SD28 code), hermetically sealed for long-term reliability. Per Renesas' ordering information, "Green parts available" indicates lead-free, RoHS-compliant construction - confirmed by the "Y" suffix option in related part numbers and compliance with JEDEC J-STD-609A marking standards.

Can the 71256S25TDB operate with a 3.3V supply?

No - the 71256S25TDB is specified only for 5V ±10% (4.5V–5.5V) operation. Its TTL-compatible inputs require V_IH ≥ 2.2V and V_IL ≤ 0.8V, and its output drive strength (±8mA) is characterized at V_CC = 5.0V. Applying 3.3V violates the Absolute Maximum Rating for V_TERM (–0.5V to +7.0V) but will not meet functional specifications for access time, current draw, or noise margins.

71256S25TDB Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: -

Package/Case:: 28-CDIP (0.300", 7.62mm)

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

71256S25TDB FAQ

1.How can I place an order for 71256S25TDB through Aetrix?

Please submit a Request for Quotation (RFQ) for 71256S25TDB 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 71256S25TDB reliable?

The price and inventory of 71256S25TDB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256S25TDB is usually 5 days.

3.What payment methods are accepted for 71256S25TDB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256S25TDB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 71256S25TDB?

71256S25TDB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 71256S25TDB 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 71256S25TDB?

For technical support, including 71256S25TDB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256S25TDB requirements.

6.How does Aetrix verify that 71256S25TDB is sourced from the original manufacturer or authorized distributors?

All 71256S25TDB 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 71256S25TDB meets industry standards.

7.What is the process for return or replacement of 71256S25TDB?

All 71256S25TDB units undergo pre-shipment inspection (PSI). If there is an issue with 71256S25TDB, 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 71256S25TDB part is unused and in its original packaging.

Return procedure for 71256S25TDB:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…