Renesas 71256L85DB

Overview

71256L85DB from Renesas is a military-grade 256K (32K × 8-bit) CMOS static RAM with 85 ns maximum access time, 5 V ±10% supply, and -55°C to +125°C operating range. It features TTL-compatible I/O, battery-backed data retention at 2 V, and low-power standby current of 1.5 μA (CMOS-level CS). Used in avionics and ruggedized embedded systems requiring nonvolatile SRAM persistence during power interruption.

For engineers reviewing the 71256L85DB datasheet, 71256L85DB pinout, 71256L85DB application, or 71256L85DB equivalent, key selection criteria include military temperature compliance, 2 V data retention capability, ceramic DIP package mechanical robustness, and verified 85 ns read/write timing under MIL-STD-883 Class B conditions.

Technical Context

This device implements a fully decoded 15-bit address space (A0–A14) driving a 262,144-bit memory array with bidirectional 8-bit data bus (I/O0–I/O7). Control logic uses three independent enables-CS for chip select, WE for write strobe, and OE for output gating-supporting both CS-controlled and WE-controlled write cycles per MIL-STD-883 timing waveforms.

It operates in three power states: active (ICC = 115 mA max), TTL-level standby (ISB = 3 mA), and CMOS-level full standby (ISB1 = 1.5 μA), with automatic transition on CS high. Data retention mode activates when VCC drops to ≥2.0 V while CS remains high, drawing ≤800 μA across all temperature grades.

Key Specifications

Pinout & Package

71256L85DB is housed in a 28-pin 600 mil ceramic dual in-line package (CD28), featuring hermetic sealing and MIL-STD-883-compliant construction for shock, vibration, and humidity resistance in defense applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-reliability SRAM applications.

Compared with 71256L85DB, the 71256S85DB trades data retention capability for slightly higher speed margin under full power, while AS7C3256B-85JCIN offers lower acquisition cost at the expense of environmental ruggedness and military certification - making 71256L85DB the sole choice for fielded systems requiring guaranteed data persistence and Class B compliance.

Availability

71256L85DB is available at Aetrix Electronics and suitable for avionics, tactical communications, and fire control systems requiring stable component supply across extended product lifecycles and defense procurement cycles.

Supply support for 71256L85DB 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 71256L series was developed specifically for military and aerospace applications demanding extended temperature operation, hermetic packaging, and battery-backed data retention - targeting systems where data integrity cannot be compromised by power interruption.

FAQ

What is the maximum operating temperature range certified for the 71256L85DB?

The 71256L85DB is fully qualified for operation from -55°C to +125°C and complies with MIL-STD-883 Class B environmental testing requirements. This range is explicitly validated in the AC Electrical Characteristics table (Table 13) and Recommended Operating Conditions (Table 5), confirming suitability for deployment in jet engine bays, desert combat vehicles, and high-altitude UAV payloads where thermal extremes are routine.

Does the 71256L85DB support true data retention at 2 V, and what is the maximum current draw in that mode?

Yes, the 71256L85DB supports guaranteed data retention at VCC ≥ 2.0 V, with ICCDR ≤ 800 μA across all temperature grades per Table 11. This specification is measured under worst-case conditions and enables reliable operation from primary lithium batteries during main power failure - a core design requirement for its target military applications.

Is the 71256L85DB pin-compatible with earlier speed grades like 71256L70DB or 71256L55DB?

Yes, all 71256L variants including 71256L85DB share identical pinout, package footprint (CD28), and electrical interface - enabling drop-in replacement within the same temperature grade. Timing parameters scale with speed grade, but address decoding, control logic, and I/O behavior remain functionally identical across the L-series family.

What package type does the 71256L85DB use, and why is it significant for military applications?

The 71256L85DB uses a 28-pin 600 mil ceramic dual in-line package (CD28), specified in the Ordering Information table (page 10). Its hermetic ceramic construction provides superior moisture resistance, thermal stability, and mechanical robustness compared to plastic packages - essential for long-term reliability in humid coastal deployments, high-vibration armored vehicles, and sealed airborne enclosures.

How does the standby power consumption of the 71256L85DB compare between TTL-level and CMOS-level chip select inputs?

When CS is driven to TTL-high (>2.2 V), the 71256L85DB draws ISB = 3 mA (Table 8); when CS is driven to CMOS-high (>VCC – 0.2 V), it enters full standby drawing only ISB1 = 1.5 μA. This two-tier standby architecture allows system designers to optimize power savings based on available control voltage levels - critical for battery-constrained platforms like dismounted soldier radios.