Renesas 7164L85DB

Overview

The 7164L85DB from Renesas Electronics is a military-grade 64K (8K × 8-bit) CMOS static RAM with 85 ns maximum access time, TTL-compatible I/O, single 5V supply operation, and battery backup data retention down to 2V. It features dual chip select (CS1/CS2) for low-power standby mode and is packaged in a 28-pin 600 mil CERDIP for high-reliability embedded systems requiring stable memory in harsh environments.

For engineers reviewing the 7164L85DB datasheet, 7164L85DB pinout, 7164L85DB application, or 7164L85DB equivalent, this page delivers verified timing parameters, military-grade DC/AC specifications, true standby current values, pin-accurate terminal roles, and confirmed drop-in alternatives - all validated against Renesas' official 7164S/L datasheet (Rev. Jul.30.20).

Technical Context

The 7164L85DB implements fully static asynchronous architecture-no clocks or refresh required-and uses dual chip select logic where CS2 powers down CS1 but not vice versa. Its low-power (L) variant enables data retention at VCC ≥ 2.0 V with ICCDR ≤ 300 µA over –55°C to +125°C.

Address access time (tAA) is guaranteed ≤85 ns across the full military temperature range (–55°C to +125°C), with read cycle time (tRC) ≤85 ns and write cycle time (tWC) ≤85 ns. Standby current (ISB) is ≤5 µA at VCC = 5.0 V and TA = +25°C, and input/output leakage currents are specified at ±2 µA.

Key Specifications

Pinout & Package

Package: 28-pin 600 mil CERDIP (CD28), hermetically sealed ceramic dual in-line package with glass-sealed leads for moisture resistance and thermal stability in extended military temperature operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar static RAM applications.

Compared with 7164S85DB and AS6C62256-85ZIN, the 7164L85DB uniquely combines military temperature range, hermetic CERDIP packaging, sub-5 µA standby current, and 2V data retention-making it irreplaceable in battery-backed, high-reliability defense systems where pin-for-pin substitution is not feasible.

Availability

The 7164L85DB is available at Aetrix Electronics and suitable for avionics flight control, tactical radio secure boot, ground vehicle engine control, and military data logger applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 7164L85DB 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 delivering trusted embedded solutions for automotive, industrial, infrastructure, and IoT applications, with deep heritage in high-reliability memory and microcontroller design.

The 7164L85DB belongs to Renesas' legacy IDT-branded CMOS static RAM product line, engineered specifically for military and aerospace applications demanding MIL-STD-883 qualification, hermetic packaging, and guaranteed data retention under brownout conditions.

FAQ

What is the maximum operating temperature range for the 7164L85DB?

The 7164L85DB is rated for –55°C to +125°C operation and is fully compliant with MIL-STD-883, Class B. This specification is verified across all AC and DC parameters in the Renesas datasheet (Rev. Jul.30.20), including access time, standby current, and data retention behavior. The 7164L85DB must be operated within this range to maintain guaranteed performance and reliability.

Does the 7164L85DB support battery backup operation, and what is the minimum retention voltage?

Yes, the 7164L85DB supports battery backup operation with guaranteed data retention down to VCC = 2.0 V, as specified in Table 10 (Data Retention Characteristics) of the Renesas datasheet. This feature is exclusive to the "L" (low-power) variant and is validated across the full military temperature range. The 7164L85DB retains data indefinitely at 2.0 V with ICCDR ≤ 300 µA.

What package type is used for the 7164L85DB, and is it hermetically sealed?

The 7164L85DB is supplied in a 28-pin 600 mil CERDIP (CD28) package - a ceramic dual in-line package with glass-sealed leads. Per the Renesas ordering information and package drawings, CD28 is explicitly defined as a hermetically sealed, moisture-resistant construction qualified for military use. This distinguishes it from plastic DIP or SOJ variants.

How does the dual chip select (CS1/CS2) logic function on the 7164L85DB?

The 7164L85DB uses asymmetric dual chip select logic: CS1 is active-low and CS2 is active-high. As stated in the Truth Table (Table 2), CS2 forces standby mode even when CS1 is asserted - meaning CS2 has priority. When CS2 goes LOW or CS1 goes HIGH, the device enters low-power standby with ISB ≤ 5 µA. This behavior is confirmed in both functional description and timing diagrams of the 7164L85DB datasheet.

Is the 7164L85DB pin-compatible with other speed grades in the 7164L family?

Yes, all 7164L variants-including 7164L20DB, 7164L25DB, and 7164L85DB-share identical pinout, package footprint (CD28), and electrical interface. The only differences are access time (tAA), power consumption (ISB/ICCDR), and corresponding speed binning. This allows direct replacement within the same package for design margining or obsolescence mitigation without PCB changes.