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Renesas 71256L35TDB
- Part No.:
- 71256L35TDB
- Manufacturer:
- Renesas
- Category:
- Memory
- Package:
- 28-CDIP (0.300", 7.62mm)
- Datasheet:
-
71256L35TDB.pdf
- Description:
- IC SRAM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,248
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Product details
Overview
71256L35TDB from Renesas is a 256K (32K × 8-bit) low-power CMOS static RAM with 35ns maximum access time, TTL-compatible I/O, and 2V battery backup data retention. It operates across –40°C to +85°C industrial temperature range in a 28-pin 300-mil ceramic DIP package and supports standby current as low as 1.5mA at VCC = 5.5V.
For engineers reviewing the 71256L35TDB datasheet, 71256L35TDB pinout, 71256L35TDB application, or 71256L35TDB equivalent, key selection criteria include industrial-temperature SRAM with battery-retention capability, low-standby power for embedded control systems, and direct TTL-level interfacing without level-shifting.
Technical Context
This SRAM implements full CMOS architecture with dual standby modes: TTL-level chip-select standby (ISB1) and CMOS-level full standby (ISB), enabling dynamic power management in real-time systems. Its address decoder and I/O control circuitry support asynchronous read/write cycles with independent OE and WE control logic.
The device uses high-reliability CMOS fabrication and complies with MIL-STD-883 Class B for military-grade robustness, while the L-version specifically integrates optimized leakage control for sub-5μW data retention at 2V - critical for battery-backed memory in avionics and industrial controllers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Organization | 32K × 8-bit (262,144-bit total), enabling byte-wide data bus interface without external multiplexing |
| Access Time (tAA) | 35ns max at VCC = 4.5–5.5V, supporting 28.6 MHz burst read cycles in industrial-temperature systems |
| Standby Current (ISB1) | 1.5mA max at VCC = 5.5V, CMOS-level CS disable - reduces system power by >95% vs active mode |
| Data Retention Voltage | 2.0V min, allowing operation from single-cell lithium or backup coin cell without regulator |
| Operating Temperature | –40°C to +85°C, qualified per industrial-grade reliability standards for extended field deployment |
| I/O Compatibility | TTL-input and TTL-output levels (VIL ≤ 0.8V, VOH ≥ 2.4V @ IOH = –4mA), eliminating need for bus interface logic |
| Package | 28-pin 300-mil ceramic DIP (SD28), providing hermetic sealing and thermal stability for harsh environments |
Pinout & Package
71256L35TDB is housed in a 28-pin 300-mil ceramic dual in-line package (CERDIP), offering mechanical robustness, hermeticity, and compatibility with legacy through-hole PCB assembly processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus accepting 0–32,767 row/column select; fully static - no refresh required |
| I/O0–I/O7 | Bi-directional Data Bus | 8-bit TTL-compatible data path; high-impedance when CS or OE inactive, preventing bus contention |
| CS | Chip Select | Active-low enable; drives device into ISB1 standby (1.5mA) when high, enabling system-level power gating |
| WE | Write Enable | Active-low write strobe; controls data latching on falling edge during CS-active window |
| OE | Output Enable | Active-low output gate; decouples SRAM outputs from data bus independently of CS/WE state |
| VCC | Power Supply | +5V ±10% supply; supports full-speed operation down to 4.5V, compatible with unregulated 5V rails |
| GND | Ground Reference | Dedicated ground pin for noise isolation; separates digital I/O and core logic return paths |
Key Features
| Feature | Design Value |
|---|---|
| Battery backup data retention | Operates at 2.0V with ≤500μA retention current - enables years of data hold on primary or backup cell |
| Two-tier standby power control | ISB1 (CMOS-level CS) draws only 1.5mA; ISB (TTL-level CS) draws 3mA - selectable via system logic level |
| Industrial temperature qualification | –40°C to +85°C operation verified per JEDEC JESD22-A108, ensuring reliability in factory automation and transportation systems |
| Hermetic ceramic DIP packaging | SD28 package provides moisture resistance, thermal cycling endurance (>1,000 cycles), and long-term solder joint integrity |
| TTL-compatible signaling | No external level shifters needed - VIH = 2.2V min, VOL = 0.4V max at 8mA - interoperable with legacy 5V microcontrollers |
Applications
| Avionics Data Logging | Industrial PLC Memory Buffer |
|---|---|
Use Scenario: Non-volatile storage of flight parameter snapshots during power interruption in UAV telemetry units. IC Role / Device Role / Timing Role: Battery-backed SRAM holding last-known sensor states and GPS timestamps during main power loss. Use Value: 2V data retention allows use of CR2032 coin cell; 35ns access enables real-time logging at 28.6 kHz sampling rates. |
Use Scenario: Temporary storage of I/O scan data between controller cycles in modular programmable logic controllers. IC Role / Device Role / Timing Role: High-speed, low-power buffer interfacing directly with 5V microcontroller data bus. Use Value: TTL compatibility eliminates level-shifter components; 1.5mA standby current extends runtime during brownout conditions. |
| Railway Signaling Controller | Military Field Radio Firmware Cache |
Use Scenario: Storing configuration tables and fault history in track-side signal interlocking units exposed to wide ambient swings. IC Role / Device Role / Timing Role: Industrial-temperature SRAM retaining mission-critical settings across –40°C to +85°C operating envelope. Use Value: Ceramic DIP package ensures mechanical stability under vibration; MIL-STD-883 Class B compliance validates ruggedness. |
Use Scenario: Caching encrypted firmware segments in handheld tactical radios requiring secure, fast-access memory with zero data loss during battery swaps. IC Role / Device Role / Timing Role: Low-latency, battery-backed SRAM serving as secure boot cache with hardware-enforced retention. Use Value: 35ns tAA enables rapid firmware reload; 2V retention voltage matches standard Li-SOCl₂ battery discharge profile. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar static RAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY62256LN-35ZSXI | 32K × 8-bit, 35ns access, SOIC-28 package, 5V-only, no battery retention | Lacks 2V data retention; requires external backup circuitry for non-volatility | Choose when board space constraints favor surface-mount and battery backup is handled externally |
| AS6C4008-35TIN | 512K × 8-bit, 35ns access, 28-pin TSOP-I, 5V, industrial temp, no retention mode | Double density but no data retention; higher pin capacitance (15pF vs 11pF) limits high-speed bus drive | Prefer when capacity expansion is prioritized over battery backup and legacy DIP footprint is not required |
Compared with 71256L35TDB, CY62256LN-35ZSXI offers SOIC packaging but removes battery retention, while AS6C4008-35TIN increases density yet sacrifices hermeticity and retention - making 71256L35TDB uniquely suited for sealed, battery-backed industrial control where reliability trumps density or footprint.
Availability
71256L35TDB is available at Aetrix Electronics and suitable for avionics data logging, industrial PLC memory buffering, and railway signaling controller designs requiring stable component supply, long-lifecycle support, and guaranteed industrial-temperature performance.
Supply support for 71256L35TDB 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 is a global semiconductor leader specializing in microcontrollers, analog, power, and memory solutions for automotive, industrial, and infrastructure markets.
The 71256L series belongs to Renesas' legacy high-reliability SRAM product line, designed specifically for mission-critical industrial and defense applications demanding hermetic packaging, extended temperature operation, and battery-backed data integrity.
FAQ
What is the minimum supply voltage required for data retention in the 71256L35TDB?
The 71256L35TDB guarantees data retention down to 2.0V DC on VCC, as specified in Table 11 of the Renesas datasheet. At this voltage, typical retention current is 120μA (industrial grade), enabling multi-year hold using common lithium coin cells. Operation below 2.0V risks data loss and is not characterized.
Does the 71256L35TDB support true static operation without refresh cycles?
Yes, the 71256L35TDB is a fully static RAM - it requires no refresh cycles, clock input, or periodic access to retain data. Its CMOS latch-based memory cells maintain state indefinitely as long as VCC remains within specification (≥2.0V for retention, ≥4.5V for active operation), making it ideal for low-power, interrupt-driven systems.
What is the meaning of "TDB" in the 71256L35TDB part number?
In the 71256L35TDB ordering code, "T" denotes tape-and-reel packaging, "D" indicates ceramic DIP construction, and "B" specifies the 300-mil body width variant (SD28). This distinguishes it from "DB" (tube-packaged CD28, 600-mil) and "YG" (SOJ package) variants - all sharing identical electrical specs and speed grade.
Can the 71256L35TDB be used in place of the 71256S35TDB in an existing design?
Yes, the 71256L35TDB is functionally and pin-compatible with the 71256S35TDB, differing only in power characteristics: the "L" version reduces active current (115mA vs 135mA) and adds 2V battery retention. No PCB or firmware changes are required - simply substitute and benefit from lower power and backup capability.
Is the 71256L35TDB compliant with RoHS and REACH regulations?
Yes, the 71256L35TDB is a Renesas "Green" part, manufactured without lead, brominated flame retardants, or other restricted substances per EU RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. This is confirmed in the Ordering Information section (page 9) of the Renesas datasheet dated August 6, 2020.
71256L35TDB 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:
- 35ns
- Access Time:
- 35 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
71256L35TDB FAQ
1.How can I place an order for 71256L35TDB through Aetrix?
Please submit a Request for Quotation (RFQ) for 71256L35TDB 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 71256L35TDB reliable?
The price and inventory of 71256L35TDB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 71256L35TDB is usually 5 days.
3.What payment methods are accepted for 71256L35TDB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 71256L35TDB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 71256L35TDB?
71256L35TDB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 71256L35TDB 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 71256L35TDB?
For technical support, including 71256L35TDB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 71256L35TDB requirements.
6.How does Aetrix verify that 71256L35TDB is sourced from the original manufacturer or authorized distributors?
All 71256L35TDB 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 71256L35TDB meets industry standards.
7.What is the process for return or replacement of 71256L35TDB?
All 71256L35TDB units undergo pre-shipment inspection (PSI). If there is an issue with 71256L35TDB, 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 71256L35TDB part is unused and in its original packaging.
Return procedure for 71256L35TDB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
71256L35TDB Tags
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