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Renesas 71256S55DB
- Part No.:
- 71256S55DB
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
71256S55DB.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,636
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Product details
Overview
71256S55DB from Renesas Electronics is a 256K (32K × 8-bit) high-speed CMOS static RAM with military-grade reliability, 55 ns maximum access time, TTL-compatible I/O, and operation across –55°C to +125°C. It features chip-select–controlled low-power standby (20 mA typical ICCSB), 5 V ±10% supply, and ceramic DIP packaging for harsh-environment avionics and defense systems.
For engineers reviewing the 71256S55DB datasheet, 71256S55DB pinout, 71256S55DB application, or 71256S55DB equivalent, this page delivers verified timing parameters, military qualification status, DC/AC electrical specs, package dimensions, and direct alternatives for legacy system sustainment and obsolescence mitigation.
Technical Context
The 71256S55DB implements a full CMOS static memory architecture with asynchronous parallel interface, address-decoded 32K × 8-bit organization, and dual-mode standby control: TTL-level CS > VIH triggers ISB mode (20 mA), while CMOS-level CS > VHC enables full standby ISB1 (20 mA). Its read cycle timing is governed by tRC = 55 ns, tAA = 55 ns, and tACS = 55 ns - all guaranteed over the full military temperature range.
It supports WE-controlled and CS-controlled write cycles with tWP = 40 ns minimum, tDW = 25 ns data-to-write overlap, and tOH = 5 ns output hold. Input/output pins are directly TTL-compatible (VIH = 2.2 V min, VIL = 0.8 V max), and the device meets MIL-STD-883 Class B for screening, including burn-in and hermeticity testing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8-bit) - provides byte-wide data bus interface without external multiplexing |
| Access Time (tAA) | 55 ns max at –55°C to +125°C - defines worst-case latency from address valid to data valid in read cycles |
| Supply Voltage | 5.0 V ±10% - compatible with standard 5 V logic rails; no external regulation required |
| Standby Current (ISB) | 20 mA max (TTL-level CS high) - enables system-level power gating during idle periods |
| Operating Temperature | –55°C to +125°C - qualified per MIL-STD-883 Class B for mission-critical aerospace and defense platforms |
| Input Compatibility | TTL-compatible inputs (VIH ≥ 2.2 V, VIL ≤ 0.8 V) - eliminates level-shifter requirements in legacy 5 V systems |
| Output Drive | VOL = 0.4 V @ 8 mA, VOH = 2.4 V @ –4 mA - ensures robust noise margin and fanout into standard TTL loads |
Pinout & Package
71256S55DB is supplied in a 28-pin 600 mil ceramic dual in-line package (CDIP), designated CD28 per Renesas ordering codes. The package is hermetically sealed, leaded, and suitable for high-reliability board assembly including solder reflow and wave processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word decoding; no external address latching required |
| I/O0–I/O7 | Bi-directional Data Bus | 8-bit parallel data path; high-impedance state when CS high or OE high during reads |
| CS | Chip Select | Active-low enable controlling device selection and standby entry (ISB/ISB1 modes) |
| WE | Write Enable | Active-low signal enabling write operations; combined with CS to define write window timing |
| OE | Output Enable | Active-low control for output drivers; allows shared bus operation with other devices |
| VCC | Power Supply | +5 V ±10% main supply; decoupling recommended within 10 mm of pin per MIL-STD-883 guidelines |
| GND | Ground Reference | Signal and power return; requires low-inductance connection to minimize ground bounce in high-speed reads |
Key Features
| Feature | Design Value |
|---|---|
| MIL-STD-883 Class B compliance | Fully screened for military applications including temperature cycling, mechanical shock, and hermeticity - eliminates need for additional qualification testing |
| 55 ns military-grade access time | Guaranteed tAA/tACS/tRC ≤ 55 ns across –55°C to +125°C - enables deterministic real-time response in flight control and radar subsystems |
| TTL-compatible I/O interface | No level translation needed when interfacing with legacy 5 V microcontrollers, FPGAs, or ASICs - reduces BOM count and layout complexity |
| Two-tier standby power control | ISB (20 mA) and ISB1 (20 mA) modes allow flexible power management based on CS logic threshold - supports both TTL and CMOS system controllers |
| Hermetic 600 mil CDIP package | Robust ceramic body with through-hole leads - withstands high-vibration environments and long-term storage without moisture ingress risk |
Applications
| Avionics Flight Control Unit | Tactical Radio Baseband Processing |
|---|---|
|
Use Scenario: Real-time storage of sensor fusion coefficients and actuator command tables in fly-by-wire ECUs. IC Role / Device Role / Timing Role: Asynchronous SRAM buffer providing sub-60 ns read access for deterministic loop execution at 10 kHz update rates. Use Value: Guaranteed 55 ns tAA across –55°C to +125°C ensures timing closure without derating, eliminating need for slower, higher-power alternatives. |
Use Scenario: Storing channel equalization lookup tables and encryption key segments in software-defined radios deployed in armored vehicles. IC Role / Device Role / Timing Role: Nonvolatile-configurable memory holding critical runtime data; accessed via FPGA-controlled parallel bus during boot and reconfiguration. Use Value: MIL-STD-883 Class B qualification ensures survivability under shock, vibration, and thermal stress encountered in mobile battlefield platforms. |
| Missile Seeker Signal Processor | Naval Radar Front-End Buffer |
|
Use Scenario: Temporary storage of digitized IF samples prior to FFT processing in infrared homing seekers. IC Role / Device Role / Timing Role: High-speed scratchpad memory interfaced directly to ADC output and DSP input buses with no glue logic. Use Value: TTL-compatible I/O and 5 V supply simplify integration with legacy radiation-hardened analog and digital ICs in compact seeker modules. |
Use Scenario: Frame buffering for pulse-Doppler radar video data between RF receiver and display processor in shipboard surveillance systems. IC Role / Device Role / Timing Role: Dual-port–emulated buffer using CS/OE/WE handshaking to manage concurrent read/write bursts from multiple subsystems. Use Value: Hermetic CDIP package prevents moisture-induced parametric drift in high-humidity maritime environments over 20+ year service life. |
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 |
|---|---|---|---|
| 71256S55TDB | Same die, 28-pin 300 mil SOJ (SD28) package - smaller footprint but non-hermetic plastic body | Limited to less severe environmental profiles; unsuitable for vacuum or high-humidity long-term deployment | Select only if board space constraints outweigh hermeticity and extended temperature requirements |
| 71256L55DB | Same CD28 package and military temp grade, but low-power variant: ISB = 1.5 mA (vs. 20 mA), 2 V data retention | Requires battery backup circuitry; not drop-in for systems relying on 5 V-only operation | Choose only when ultra-low standby power is prioritized and supplemental 2 V rail is available |
Compared with 71256S55DB, 71256S55TDB trades hermetic reliability for density, while 71256L55DB sacrifices 5 V simplicity for µW-level standby - neither offers pin-compatible replacement without design revision, making 71256S55DB the sole choice for unmodified legacy military hardware sustainment.
Availability
71256S55DB is available at Aetrix Electronics and suitable for avionics flight control units, tactical radio baseband processors, missile seeker signal processors, and naval radar front-end buffers requiring stable component supply across extended product lifecycles.
Supply support for 71256S55DB 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 71256S55DB belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for military and aerospace applications demanding MIL-STD-883 qualification, wide temperature operation, and long-term obsolescence support.
FAQ
What is the guaranteed maximum access time for 71256S55DB across its full operating temperature range?
The 71256S55DB guarantees a maximum address access time (tAA) of 55 ns across the full military temperature range of –55°C to +125°C, as confirmed in Table 13 of the Renesas datasheet. This value applies to all read cycle conditions with VCC = 5.0 V ±10%, and is validated per MIL-STD-883 test methods. No derating is required for thermal variation within spec.
Does 71256S55DB support battery backup operation for data retention?
No, the 71256S55DB is the standard-power variant and does not support battery backup data retention. That capability is exclusive to the 'L' suffix versions (e.g., 71256L55DB), which specify 2 V data retention and microamp-level standby current. The 71256S55DB operates strictly from a 5 V supply and enters standby only when CS is deasserted.
Is 71256S55DB pin-compatible with commercial-grade 71256S25DB or 71256S35DB?
Yes, 71256S55DB shares identical pinout, package (CD28), and functional interface with all speed grades in the 71256S family, including 71256S25DB and 71256S35DB. All variants use the same 28-pin ceramic DIP footprint and logic-level definitions, enabling direct substitution where timing margins permit - though system-level timing validation remains mandatory.
What packaging and screening standards apply to 71256S55DB?
The 71256S55DB is packaged in a 28-pin 600 mil ceramic dual in-line package (CD28) and is fully compliant with MIL-STD-883, Class B. Screening includes temperature cycling, steady-state life test, and hermeticity verification. Lot traceability, burn-in, and radiographic inspection are performed per Class B requirements, ensuring suitability for high-integrity defense platforms.
Can 71256S55DB be used in new designs, or is it obsolete?
Renesas has not declared 71256S55DB obsolete; however, it is categorized as a legacy product with no active roadmap development. Aetrix Electronics maintains inventory and supports long-term supply for sustaining engineering and repair programs. For new designs, Renesas recommends evaluating modern low-power SRAMs or integrated memory subsystems - but 71256S55DB remains fully supported for legacy system continuity.
71256S55DB 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:
- 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
71256S55DB FAQ
1.How can I place an order for 71256S55DB through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256S55DB 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 71256S55DB reliable?
The price and inventory of 71256S55DB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256S55DB is usually 5 days.
3.What payment methods are accepted for 71256S55DB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256S55DB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256S55DB?
71256S55DB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256S55DB 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 71256S55DB?
For technical support, including 71256S55DB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256S55DB requirements.
6.How does Aetrix verify that 71256S55DB is sourced from the original manufacturer or authorized distributors?
All 71256S55DB 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 71256S55DB meets industry standards.
7.What is the process for return or replacement of 71256S55DB?
All 71256S55DB units undergo pre-shipment inspection (PSI). If there is an issue with 71256S55DB, 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 71256S55DB part is unused and in its original packaging.
Return procedure for 71256S55DB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71256S55DB Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
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24LC01BT-I/OT
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M24C02-FMC6TG
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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