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Renesas 71256L25TDB
- Part No.:
- 71256L25TDB
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-CDIP (0.300", 7.62mm)
- Datasheet:
-
71256L25TDB.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,609
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Product details
Overview
71256L25TDB from Renesas Electronics is a 256K (32K × 8-bit) low-power CMOS static RAM with 25ns maximum access time, TTL-compatible I/O, and battery-backed data retention at 2V. It operates across the military temperature range (–55°C to +125°C), features automatic standby mode on chip select high, and is packaged in a 28-pin 300-mil ceramic DIP (SD28) for high-reliability embedded systems.
For engineers reviewing the 71256L25TDB datasheet, 71256L25TDB pinout, 71256L25TDB application, or 71256L25TDB equivalent, key selection criteria include military-grade timing consistency, sub-5μW standby power, 2V data retention capability, and MIL-STD-883 Class B compliance - critical for avionics, defense computing, and ruggedized control units.
Technical Context
The 71256L25TDB implements a full CMOS static memory architecture with asynchronous parallel interface, supporting independent read/write cycles via separate WE, OE, and CS controls. Its dual standby modes - TTL-level (ISB) and CMOS-level (ISB1) - deliver 3mA and 1.5mA supply current respectively at VCC = 5.5V, enabling system-level power optimization without clock gating.
Timing is defined by strict AC parameters including tAA ≤ 25ns, tACS ≤ 25ns, and tRC ≤ 25ns under military conditions (–55°C to +125°C), with guaranteed tCHZ ≤ 15ns and tOHZ ≤ 15ns for clean bus release. Data retention at 2V is validated across all temperature grades, with ICCDR ≤ 120μA at 3.0V and ≤ 800μA at 2.0V.
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 at –55°C to +125°C - ensures deterministic timing in real-time military firmware |
| Supply Voltage | 4.5V to 5.5V - compatible with standard 5V logic rails and tolerant of rail droop |
| Standby Current (ISB1) | 1.5mA max at VCC = 5.5V - enables ultra-low-power hold mode during processor sleep |
| Data Retention Voltage | 2.0V min - supports backup from single LiSOCl₂ or primary lithium cells |
| Input/Output Compatibility | TTL-level - interfaces directly with 74LS, 74F, and microcontroller GPIO without level shifters |
| Operating Temperature | –55°C to +125°C - qualified per MIL-STD-883 Class B for mission-critical environments |
Pinout & Package
71256L25TDB is housed in a 28-pin 300-mil ceramic dual in-line package (CERDIP, SD28), hermetically sealed for moisture resistance and thermal stability in harsh environments. Pin layout follows industry-standard 28-pin DIP footprint with 0.3-inch width and 0.1-inch lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus for full 32K-word decoding; CMOS inputs with VIH ≥ 2.2V, VIL ≤ 0.8V |
| I/O0–I/O7 | Bi-directional Data Bus | 8-bit TTL-compatible data path; high-impedance when CS or OE inactive |
| CS | Chip Select | Active-low enable; drives device into ISB1 standby (1.5mA) when held >VHC |
| WE | Write Enable | Active-low write control; concurrent LOW CS+WE initiates write cycle (tWP ≥ 20ns) |
| OE | Output Enable | Active-low output gate; controls data bus drive without affecting internal state |
| VCC | Power Supply | +5V supply pin; decoupling required within 0.5 inch for noise immunity |
| GND | Ground Reference | Signal and power ground; must be low-inductance connection to minimize switching noise |
Key Features
| Feature | Design Value |
|---|---|
| Battery backup data retention | Operates down to 2.0V with ICCDR ≤ 120μA at 3.0V - enables years of SRAM state hold on primary cell |
| Two-tier standby power management | ISB = 3mA (TTL CS), ISB1 = 1.5mA (CMOS CS) - selectable via system-level voltage threshold design |
| MIL-STD-883 Class B qualification | Fully tested per mechanical shock, temperature cycling, and burn-in protocols - certified for flight-critical hardware |
| Direct TTL compatibility | No external level translation needed for 74-series or legacy microprocessor buses - reduces BOM count and layout complexity |
| Hermetic ceramic DIP packaging | SD28 300-mil CERDIP - provides superior moisture barrier and thermal conductivity vs. plastic packages |
Applications
| Avionics Flight Control Unit | Tactical Radio Baseband Processor |
|---|---|
Use Scenario: Real-time servo loop buffering and configuration storage in fly-by-wire ECUs operating at –55°C to +125°C. IC Role / Device Role / Timing Role: Primary working memory for ARM7TDMI-based controller; accessed synchronously with 25ns timing budget. Use Value: Guaranteed tAA ≤ 25ns across full military temp range eliminates timing margin uncertainty in safety-critical control paths. |
Use Scenario: Frame buffer and protocol stack scratchpad in software-defined radios deployed in desert and arctic environments. IC Role / Device Role / Timing Role: Low-power SRAM for burst-mode DSP data exchange; enters ISB1 mode between TDMA slots. Use Value: 1.5mA ISB1 current at 5.5V extends battery life >3× vs. standard SRAM during receive-only intervals. |
| Secure Crypto Module | Artillery Fire Control Computer |
Use Scenario: Key schedule storage and intermediate cipher state in FIPS 140-2 Level 3 tamper-resistant hardware. IC Role / Device Role / Timing Role: Tamper-evident volatile memory; powered from isolated 2V lithium backup during main supply removal. Use Value: Validated 2V data retention ensures cryptographic state persistence through 100ms power interruption events. |
Use Scenario: Ballistic computation scratchpad in mobile artillery systems subject to vibration, thermal shock, and EMI. IC Role / Device Role / Timing Role: High-reliability SRAM interfaced to radiation-hardened 80C86 derivative; accessed via ISA-like bus. Use Value: Hermetic SD28 CERDIP package withstands 20G vibration and 1000-cycle thermal cycling per MIL-STD-883 Method 1010. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar static RAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IS61LV25616AL-10TLI | 3.3V-only supply, 10ns access, 44-pin TSOP - no military temp or 2V retention | Commercial industrial control; unsuitable for 5V legacy buses or battery backup | Select only for new 3.3V designs requiring higher speed and lower cost |
| AS6C4008-25ZIN | 5V operation, 25ns access, 28-pin SOJ - commercial temp only (0°C to +70°C), no MIL-STD-883 | Cost-sensitive test equipment; lacks environmental ruggedness and long-term data retention | Use where military qualification and extended temperature are not required |
Compared with 71256L25TDB, IS61LV25616AL-10TLI offers faster access but requires full 3.3V redesign and forfeits battery backup; AS6C4008-25ZIN matches speed and voltage but lacks military qualification, making it inappropriate for field-deployed defense systems.
Availability
71256L25TDB is available at Aetrix Electronics and suitable for avionics, tactical communications, and fire control systems requiring stable component supply, long-lifecycle support, and guaranteed MIL-STD-883 Class B conformance.
Supply support for 71256L25TDB 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 infrastructure markets.
The 71256L25TDB belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for military and aerospace applications demanding guaranteed performance across extreme temperatures and long-term data integrity.
FAQ
What is the maximum operating temperature range for the 71256L25TDB?
The 71256L25TDB is rated for continuous operation from –55°C to +125°C and is fully qualified to MIL-STD-883 Class B, including temperature cycling, mechanical shock, and steady-state life testing. This makes the 71256L25TDB appropriate for engine-mounted avionics, missile guidance sections, and other high-thermal-stress environments where commercial or industrial grade parts would fail.
Does the 71256L25TDB support true battery backup operation below 5V?
Yes - the 71256L25TDB guarantees data retention at VCC = 2.0V minimum, with typical ICCDR of 120μA at 3.0V and ≤800μA at 2.0V. This allows direct connection to a single 2V lithium thionyl chloride (LiSOCl₂) cell for multi-year memory hold without regulators or charge pumps, a capability confirmed in Renesas datasheet Table 11.
Is the 71256L25TDB pin-compatible with other members of the 71256 family?
Yes - the 71256L25TDB shares identical pinout, package (SD28), and functional interface with all 71256S/L variants in 28-pin DIP format, including 71256S25TDB and 71256L35TDB. Address, data, and control signals map identically; only timing parameters and power characteristics differ between S (standard) and L (low-power) versions.
What is the standby current consumption of the 71256L25TDB under full CMOS-level disable?
When CS is driven above VHC (VCC – 0.2V), the 71256L25TDB enters full standby mode (ISB1) drawing ≤1.5mA at VCC = 5.5V, as specified in Renesas datasheet Table 8. This is distinct from TTL-level standby (ISB = ≤3mA), and requires precise voltage threshold control on the CS line to achieve minimum power.
Can the 71256L25TDB be used in new designs despite its legacy status?
Yes - although originally introduced by IDT and later rebranded by Renesas, the 71256L25TDB remains actively supported with documented availability, traceable sourcing, and lifecycle coordination. Its MIL-STD-883 qualification, hermetic packaging, and 2V retention make it irreplaceable for sustaining engineering of deployed military platforms where redesign is prohibited or cost-prohibitive.
71256L25TDB 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
71256L25TDB FAQ
1.How can I place an order for 71256L25TDB through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256L25TDB 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 71256L25TDB reliable?
The price and inventory of 71256L25TDB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256L25TDB is usually 5 days.
3.What payment methods are accepted for 71256L25TDB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256L25TDB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256L25TDB?
71256L25TDB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256L25TDB 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 71256L25TDB?
For technical support, including 71256L25TDB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256L25TDB requirements.
6.How does Aetrix verify that 71256L25TDB is sourced from the original manufacturer or authorized distributors?
All 71256L25TDB 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 71256L25TDB meets industry standards.
7.What is the process for return or replacement of 71256L25TDB?
All 71256L25TDB units undergo pre-shipment inspection (PSI). If there is an issue with 71256L25TDB, 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 71256L25TDB part is unused and in its original packaging.
Return procedure for 71256L25TDB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71256L25TDB Tags
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