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Renesas 71256L55TDB
- Part No.:
- 71256L55TDB
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-CDIP (0.300", 7.62mm)
- Datasheet:
-
71256L55TDB.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,647
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Product details
Overview
71256L55TDB from Renesas Electronics is a 256K (32K × 8-bit) low-power CMOS static RAM with military-grade reliability, 55 ns maximum access time, –55°C to +125°C operating temperature range, and 2V battery backup data retention. It serves as nonvolatile system memory in avionics, radar processors, and hardened embedded controllers requiring deterministic timing and long-term data hold under power loss.
For engineers reviewing the 71256L55TDB datasheet, 71256L55TDB pinout, 71256L55TDB application, or 71256L55TDB equivalent, key selection criteria include military-qualified standby current (1.5 mA), TTL-compatible I/O, ceramic DIP package mechanical robustness, and guaranteed AC timing across full temperature range without derating.
Technical Context
This device implements a fully decoded 15-bit address space (A0–A14) driving a 32K × 8-bit memory array with asynchronous read/write control via CS, WE, and OE. Its dual standby modes-TTL-level (ISB = 3 mA) and CMOS-level (ISB1 = 1.5 mA)-enable precise power-state management in mission-critical systems where thermal dissipation and battery life are constrained.
The 71256L55TDB uses high-reliability CMOS process compliant with MIL-STD-883 Class B, supporting deterministic 55 ns tAA and tACS timing at VCC = 5.0 V ±10% across –55°C to +125°C. Input/output pins meet TTL voltage thresholds (VIH = 2.2 V min, VIL = 0.8 V max), ensuring direct interface with legacy 5V logic without level translation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 32K × 8-bit (262,144 bits), enabling byte-wide data bus interfacing without multiplexing |
| Access Time (tAA) | 55 ns max at –55°C to +125°C, guaranteeing deterministic read latency in real-time military systems |
| Supply Voltage | 5.0 V ±10%, compatible with standard 5V military power rails and tolerant of input ripple |
| Standby Current (ISB1) | 1.5 mA max at VCC = 5.5 V, enabling >1-year battery backup from 2V source with µW-level retention |
| Data Retention Voltage | 2.0 V min, allowing operation from depleted batteries or auxiliary low-voltage hold circuits |
| Operating Temperature | –55°C to +125°C, qualified per MIL-STD-883 Class B for deployment in engine bays, missile guidance, and space-qualified platforms |
| Package Type | 28-pin 300-mil ceramic DIP (SD28), providing hermetic sealing and thermal stability unmatched by plastic packages |
Pinout & Package
71256L55TDB is housed in a 28-pin 300-mil ceramic dual in-line package (CERDIP), offering hermeticity, thermal cycling resilience, and MIL-STD-883 compliance. The package supports through-hole mounting and withstands harsh environmental stress including shock, vibration, and humidity exposure.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit parallel address bus accepting full 32K address space; TTL-compatible inputs eliminate need for bus buffers |
| I/O0–I/O7 | Bi-directional Data Bus | 8-bit TTL-compatible data path supporting simultaneous read/write cycles without external transceivers |
| CS | Chip Select | Active-low enable controlling full device standby entry/exit; CMOS-level threshold enables ultra-low ISB1 mode |
| WE | Write Enable | Active-low signal qualifying write cycles; timing-critical for tWP (40 ns min) and tDW (25 ns min) compliance |
| OE | Output Enable | Active-low control for output drivers; independent of WE, enabling read-modify-write sequences |
| VCC | Power Supply | 5V primary supply pin; decoupling required within 0.5 inch to maintain 55 ns timing integrity |
| GND | Ground Reference | Signal and power ground return; dedicated pin minimizes noise coupling into memory array |
Key Features
| Feature | Design Value |
|---|---|
| Battery backup data retention | Operates down to 2.0 V with ≤500 µA ICCDR, enabling >10-year data hold on coin-cell batteries in unpowered systems |
| MIL-STD-883 Class B qualification | Full screening including burn-in, temperature cycling, and hermeticity testing ensures field reliability in defense platforms |
| Dual standby power modes | ISB = 3 mA (TTL CS high) and ISB1 = 1.5 mA (CMOS CS high) allow hierarchical power management in multi-rail systems |
| TTL-compatible I/O | Direct interface with 5V microcontrollers, FPGAs, and ASICs eliminates level-shifter components and PCB area |
| Hermetic ceramic DIP package | SD28 footprint provides moisture resistance, thermal stability, and mechanical ruggedness exceeding plastic SOJ alternatives |
Applications
| Avionics Flight Control Memory | Tactical Radar Frame Buffer |
|---|---|
Use Scenario: Storing real-time sensor fusion coefficients and flight envelope limits in fly-by-wire ECUs subject to extreme thermal cycling and EMI. IC Role / Device Role / Timing Role: Nonvolatile configuration memory holding critical calibration tables during engine start-up and brownout events. Use Value: 2V data retention preserves flight-critical parameters for >10 years without external backup power, reducing system BOM count. |
Use Scenario: Buffering pulse-Doppler processing results between FPGA-based signal chains in airborne early warning systems. IC Role / Device Role / Timing Role: High-speed scratchpad memory synchronizing ADC samples and FFT outputs with deterministic 55 ns read latency. Use Value: MIL-qualified timing guarantees no cycle stretching across –55°C to +125°C, eliminating timing margin uncertainty in radar timing budgets. |
| Missile Guidance Onboard Storage | Secure Communications Crypto Key Vault |
Use Scenario: Holding encrypted target coordinates and trajectory updates in guided munitions exposed to high-G launch and re-entry thermal profiles. IC Role / Device Role / Timing Role: Radiation-tolerant, hermetically sealed storage for mission-critical navigation vectors accessed during terminal phase. Use Value: Ceramic DIP package withstands 20,000 g shock and 1000+ thermal cycles, ensuring data integrity where plastic packages would fracture. |
Use Scenario: Securing cryptographic keys in SATCOM terminals deployed in forward operating bases with unreliable grid power. IC Role / Device Role / Timing Role: Tamper-resistant memory storing AES-256 keys with zero-volt retention capability during forced power-down. Use Value: 1.5 mA ISB1 standby current extends battery life to 5+ years in always-on crypto modules, reducing maintenance frequency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar static RAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY62256LN-55ZSXI | 55 ns access, 32K × 8, SOIC-28 package, industrial temp only (–40°C to +85°C) | Lacks MIL-STD-883 qualification and hermetic packaging; unsuitable for aerospace or defense deployments | Select when cost-sensitive commercial systems require same speed but do not demand military reliability or extended temperature range |
| AS6C4008-55TIN | 55 ns access, 512K × 8 organization, TSOP-32 package, industrial temp only | Double density but incompatible pinout and higher standby current (5 mA); requires PCB redesign | Choose only if memory capacity expansion is prioritized over drop-in replacement and military qualification is unnecessary |
Compared with CY62256LN-55ZSXI and AS6C4008-55TIN, the 71256L55TDB uniquely delivers MIL-STD-883 Class B qualification, 2V data retention, and hermetic ceramic DIP packaging-making it the sole option for systems where environmental survivability and long-term unpowered data integrity are non-negotiable.
Availability
71256L55TDB is available at Aetrix Electronics and suitable for avionics, radar subsystems, and missile guidance systems requiring stable component supply across extended product lifecycles and defense procurement cycles.
Supply support for 71256L55TDB 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 71256L55TDB belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for military and aerospace applications demanding guaranteed performance across extreme temperature, radiation, and mechanical stress environments.
FAQ
What is the maximum operating temperature range for the 71256L55TDB?
The 71256L55TDB operates from –55°C to +125°C and is fully qualified to MIL-STD-883 Class B across this range. This specification is verified through temperature cycling, burn-in, and parametric testing per military standards-not extrapolated or derated. All AC timing parameters, including 55 ns tAA, are guaranteed at both extremes without margin reduction.
Does the 71256L55TDB support true battery backup operation below 5V?
Yes-the 71256L55TDB retains data at VCC = 2.0 V minimum, consuming ≤500 µA in retention mode. This is measured and specified in Table 11 of the Renesas datasheet under "Data Retention Characteristics." The device maintains full data integrity without refresh or external circuitry, making it suitable for long-term hold in battery-backed systems.
Is the 71256L55TDB pin-compatible with other 71256 variants such as the 71256S55TDB?
Yes-the 71256L55TDB shares identical pinout, package (SD28), and functional block diagram with all 71256S/L variants. The 'L' suffix denotes low-power design (lower ISB/ISB1), while 'S' indicates standard power; both use the same 28-pin ceramic DIP footprint and electrical interface, enabling direct substitution where power budget allows.
What is the standby current specification for the 71256L55TDB under CMOS-level chip select?
The 71256L55TDB draws ≤1.5 mA ISB1 when CS is held above VHC (VCC − 0.2 V) at VCC = 5.5 V and f = 0, as specified in Table 8 of the Renesas datasheet. This ultra-low standby mode is distinct from TTL-level standby (ISB = 3 mA) and enables extended battery life in always-on military systems.
Can the 71256L55TDB be used in new designs despite its legacy status?
Yes-the 71256L55TDB remains actively supported by Renesas with documented availability, traceable sourcing, and lifecycle coordination. Its rebranding in the 2020 datasheet confirms ongoing manufacturing and obsolescence management. Aetrix Electronics provides full supply chain continuity for this part in defense and industrial programs requiring long-term component stability.
71256L55TDB 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:
- 55ns
- Access Time:
- 55 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
71256L55TDB FAQ
1.How can I place an order for 71256L55TDB through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256L55TDB 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 71256L55TDB reliable?
The price and inventory of 71256L55TDB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256L55TDB is usually 5 days.
3.What payment methods are accepted for 71256L55TDB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256L55TDB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256L55TDB?
71256L55TDB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256L55TDB 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 71256L55TDB?
For technical support, including 71256L55TDB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256L55TDB requirements.
6.How does Aetrix verify that 71256L55TDB is sourced from the original manufacturer or authorized distributors?
All 71256L55TDB 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 71256L55TDB meets industry standards.
7.What is the process for return or replacement of 71256L55TDB?
All 71256L55TDB units undergo pre-shipment inspection (PSI). If there is an issue with 71256L55TDB, 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 71256L55TDB part is unused and in its original packaging.
Return procedure for 71256L55TDB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71256L55TDB Tags
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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AT24C08C-STUM-T
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