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Renesas 71256S85DB
- Part No.:
- 71256S85DB
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
71256S85DB.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,470
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Product details
Overview
71256S85DB from Renesas Electronics is a 256K (32K × 8-bit) high-speed CMOS static RAM designed for military-grade embedded memory applications requiring reliable, low-power operation across –55°C to +125°C. It features 85ns maximum address access time, 5V ±10% supply voltage, TTL-compatible I/O, and full MIL-STD-883 Class B compliance. Used in avionics control units, radar signal buffers, and hardened data loggers where deterministic timing and data retention under power loss are critical.
For engineers reviewing the 71256S85DB datasheet, 71256S85DB pinout, 71256S85DB application, or 71256S85DB equivalent, key selection considerations include military temperature support, 85ns read/write cycle timing, ceramic DIP package mechanical robustness, standby current of 20mA (TTL-level CS), and compatibility with legacy 28-pin SRAM-based board designs.
Technical Context
The 71256S85DB implements a fully decoded 15-bit address space (A0–A14) driving a 32K × 8-bit memory array with asynchronous read/write control via independent CS, WE, and OE inputs. Its architecture supports both CS-controlled and WE-controlled write cycles, with guaranteed tRC = 85ns and tAA = 85ns max across the full military temperature range.
It operates in three power states: active (ICC = 135mA typ.), TTL-level standby (ISB = 20mA), and CMOS-level full standby (ISB1 = 20mA). Input and output circuits meet TTL voltage thresholds (VIH ≥ 2.2V, VIL ≤ 0.8V), ensuring direct interface with 5V logic without level-shifting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 32K × 8-bit (262,144 bits), fixed parallel interface with no internal refresh required |
| Access Time (tAA) | 85ns max at –55°C to +125°C - guarantees deterministic read latency in real-time systems |
| Supply Voltage | 5V ±10% (4.5V–5.5V) - compatible with standard 5V military power rails |
| Operating Temperature | –55°C to +125°C - qualified per MIL-STD-883 Class B for aerospace and defense platforms |
| Standby Current (ISB) | 20mA max when CS > VIH - enables system-level power gating without external circuitry |
| I/O Compatibility | TTL-input and TTL-output - directly interfaces with 74LS/ALS logic and microprocessor buses |
| Package | 28-pin 600-mil ceramic DIP (CD28) - hermetically sealed, high-reliability mechanical form factor |
Pinout & Package
71256S85DB is housed in a 28-pin 600-mil ceramic dual in-line package (CD28), featuring hermetic sealing and lead finish suitable for high-reliability military assembly processes. Pin numbering follows standard DIP top-view orientation with pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit unidirectional address bus; fully decoded to select one of 32K locations |
| I/O0–I/O7 | Bi-directional Data Bus | 8-bit shared input/output path; high-impedance when CS or OE inactive |
| CS | Chip Select | Active-low enable; drives device into low-power standby when HIGH |
| WE | Write Enable | Active-low write strobe; controls data latching during CS-active window |
| OE | Output Enable | Active-low output gate; isolates I/O pins from bus when deasserted |
| VCC | Power Supply | +5V ±10% main supply; powers core logic and I/O drivers |
| GND | Ground Reference | 0V return path for all internal circuits and I/O signaling |
Key Features
| Feature | Design Value |
|---|---|
| MIL-STD-883 Class B compliance | Fully tested per military screening requirements including burn-in, thermal cycling, and hermeticity - validated for flight-critical subsystems |
| 85ns military-grade timing | Guaranteed tRC and tAA ≤ 85ns over –55°C to +125°C - eliminates timing margin uncertainty in hard real-time firmware |
| TTL-compatible I/O | VIH ≥ 2.2V, VIL ≤ 0.8V, VOH ≥ 2.4V, VOL ≤ 0.4V - interoperable with legacy 5V microcontrollers and FPGAs without translators |
| Two-tier standby mode | ISB = 20mA (TTL CS), ISB1 = 20mA (CMOS CS) - allows flexible power management based on system control logic levels |
| Hermetic CDIP packaging | 600-mil ceramic DIP (CD28) with solder-dip leads - provides moisture resistance and long-term reliability in harsh environments |
Applications
| Avionics Flight Control Memory | Radar Signal Processing Buffer |
|---|---|
|
Use Scenario: Storing real-time sensor fusion coefficients and actuator command tables in fly-by-wire ECUs. IC Role / Device Role / Timing Role: Asynchronous SRAM providing deterministic 85ns read/write access for safety-critical control loops. Use Value: MIL-STD-883 qualification ensures uninterrupted operation during extreme thermal transients and vibration encountered in jet aircraft. |
Use Scenario: Temporary storage of digitized IF samples between ADC capture and FFT processing in ground-based radar receivers. IC Role / Device Role / Timing Role: High-speed buffer enabling burst-mode data transfer without DMA arbitration overhead. Use Value: TTL-compatible I/O and 85ns timing allow direct connection to Xilinx Spartan-6 FPGA memory controllers using minimal glue logic. |
| Tactical Radio Baseband Storage | Hardened Data Logger |
|
Use Scenario: Holding encrypted voice packet headers and channel state information in manpack radios operating in desert environments. IC Role / Device Role / Timing Role: Non-volatile-capable memory supporting rapid context switching between encryption modes. Use Value: –55°C to +125°C rating ensures stable operation inside sealed enclosures exposed to direct sunlight or cold-soak conditions. |
Use Scenario: Capturing telemetry streams from missile test flights where power interruption may occur mid-mission. IC Role / Device Role / Timing Role: Primary working memory with automatic entry into low-power standby upon main rail collapse. Use Value: 20mA standby current enables extended battery-backed operation using discrete 2V backup supplies without redesigning power architecture. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-reliability SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY62128EV30LL-85ZSXI | 32K × 8-bit, 85ns, 5V, SOIC-28, industrial temp only (–40°C to +85°C) | Lacks MIL-STD-883 qualification and extended temperature range | Preferred for cost-sensitive commercial or industrial systems where military screening is not mandated |
| AS6C4008-85ZIN | 32K × 8-bit, 85ns, 5V, TSOP-28, industrial temp only (–40°C to +85°C), lower ICC (100mA typ.) | No hermetic packaging; not MIL-qualified; incompatible pinout (TSOP vs. DIP) | Suitable for space-constrained PCBs where reworkability and density outweigh environmental ruggedness needs |
Compared with 71256S85DB, CY62128EV30LL-85ZSXI offers identical speed and organization but lacks military qualification and extended temperature support, while AS6C4008-85ZIN trades hermetic reliability and DIP compatibility for smaller footprint and lower active power - making 71256S85DB the sole choice when MIL-STD-883 Class B compliance and –55°C to +125°C operation are mandatory.
Availability
71256S85DB is available at Aetrix Electronics and suitable for avionics flight control systems, radar signal processing modules, and tactical radio baseband designs requiring stable component supply across extended product lifecycles and stringent environmental certifications.
Supply support for 71256S85DB 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 71256S85DB belongs to Renesas' legacy high-reliability SRAM product line, engineered specifically for military and aerospace applications demanding guaranteed performance across extreme temperature ranges and rigorous quality screening.
FAQ
What is the maximum operating temperature range for the 71256S85DB?
The 71256S85DB is rated for continuous operation from –55°C to +125°C and is fully qualified per MIL-STD-883 Class B, including thermal cycling and burn-in tests. This specification is explicitly confirmed in the Absolute Maximum Ratings and Recommended Operating Conditions tables of the Renesas datasheet revision Aug.06.20, and applies to the CD28 ceramic DIP package variant.
Does the 71256S85DB support battery backup data retention?
No - the 71256S85DB is the standard-power variant ('S') and does not include battery backup capability. Only the 'L' suffix versions (e.g., 71256L85DB) specify 2V data retention and microamp-level standby current. The 71256S85DB exhibits ISB = 20mA in TTL-level standby, confirming its non-retentive design per DC Electrical Characteristics Table 8.
Is the 71256S85DB pin-compatible with other 28-pin SRAMs like the 62256 or HM62256?
Yes - the 71256S85DB uses the industry-standard 28-pin SRAM pinout: A0–A14 on pins 1–2, 12, 15, 19–22; I/O0–I/O7 on pins 10–11, 13–14, 16–18; CS on pin 20; WE on pin 22; OE on pin 21; VCC on pin 24; GND on pin 12. This matches JEDEC MS-011AC and is electrically and physically compatible with 32K × 8-bit devices such as the 62256 family when used in 5V systems.
What is the meaning of 'DB' in the part number 71256S85DB?
Per Renesas' Ordering Information (page 10), 'DB' denotes the 600-mil ceramic DIP package (CD28) with tube packaging. The 'D' stands for DIP, and 'B' indicates tube delivery format. This distinguishes it from 'TDB', which specifies tape-and-reel packaging for the same CD28 package, and from 'YG' or 'TDB' variants used with SOJ packages.
Can the 71256S85DB be operated at 3.3V?
No - the 71256S85DB is strictly a 5V device. Its Recommended Operating Conditions specify VCC = 5V ±10% (4.5V–5.5V), and DC Electrical Characteristics (Table 6) define VIH and VIL thresholds relative to 5V logic levels. Operation below 4.5V violates the minimum supply specification and risks incorrect read/write behavior, especially across the full military temperature range.
71256S85DB 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:
- 85ns
- Access Time:
- 85 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
71256S85DB FAQ
1.How can I place an order for 71256S85DB through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256S85DB 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 71256S85DB reliable?
The price and inventory of 71256S85DB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256S85DB is usually 5 days.
3.What payment methods are accepted for 71256S85DB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256S85DB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256S85DB?
71256S85DB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256S85DB 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 71256S85DB?
For technical support, including 71256S85DB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256S85DB requirements.
6.How does Aetrix verify that 71256S85DB is sourced from the original manufacturer or authorized distributors?
All 71256S85DB 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 71256S85DB meets industry standards.
7.What is the process for return or replacement of 71256S85DB?
All 71256S85DB units undergo pre-shipment inspection (PSI). If there is an issue with 71256S85DB, 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 71256S85DB part is unused and in its original packaging.
Return procedure for 71256S85DB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71256S85DB Tags
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