Renesas 7164L20TDB

Overview

7164L20TDB from Renesas Electronics is a military-grade 64K (8K × 8-bit) CMOS static RAM with 20 ns maximum address access time, TTL-compatible I/O, three-state outputs, and battery backup data retention down to 2 V. It operates from a single 5 V supply and supports standby power reduction via dual chip select control (CS1/CS2). Used in avionics, radar processors, and hardened embedded controllers requiring non-volatile memory persistence during brownout.

For engineers reviewing the 7164L20TDB datasheet, 7164L20TDB pinout, 7164L20TDB application, or 7164L20TDB equivalent, key selection criteria include military temperature range (–55°C to +125°C), CERDIP-28 package compatibility, 2 V data retention capability, and CS-controlled write timing compliance per MIL-STD-883 Class B.

Technical Context

The 7164L20TDB implements fully static asynchronous operation-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 while maintaining full read/write functionality at 5.0 V ±10%.

It features TTL-compatible input thresholds (VIH ≥ 2.2 V, VIL ≤ 0.8 V), output drive strength of IOH = –4 mA / IOL = 8 mA, and supports three-state output control via OE and CS signals. Standby current ISB is guaranteed ≤ 5 µA across military temperature range.

Key Specifications

Pinout & Package

28-pin 300-mil CERDIP (SD28) package with 0.3-inch width, ceramic body, and solder-leaded terminations. Designed for high-reliability military PCBs requiring thermal cycling resilience and long-term hermeticity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 7164S20TDB and AS6C62256-20TIN, the 7164L20TDB uniquely combines military temperature rating, 2 V data retention, and 28-pin CERDIP packaging - making it irreplaceable in legacy 5 V, battery-backed, high-reliability systems where layout and voltage constraints prohibit redesign.

Availability

7164L20TDB is available at Aetrix Electronics and suitable for avionics, radar signal processing, and missile guidance systems requiring stable component supply across extended product lifecycles and obsolescence-sensitive programs.

Supply support for 7164L20TDB 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.

The IDT7164 family was originally developed by Integrated Device Technology and acquired by Renesas; this product line targets high-reliability, military-qualified memory applications demanding long-term availability and rigorous environmental screening.

FAQ

What is the maximum operating temperature range for the 7164L20TDB?

The 7164L20TDB is rated for operation from –55°C to +125°C and is fully qualified to MIL-STD-883 Class B. This military temperature range ensures reliable performance in harsh environments such as jet engine bays, missile canisters, and satellite payload compartments where thermal extremes are routine. The 7164L20TDB maintains all specified timing and retention parameters across this full span without derating.

Does the 7164L20TDB support true battery backup operation?

Yes - the 7164L20TDB supports true battery backup operation with guaranteed data retention at VCC ≥ 2.0 V. When main power drops below operational threshold, the device automatically enters retention mode with ISB ≤ 5 µA, preserving stored data indefinitely as long as backup voltage remains above 2.0 V. This behavior is intrinsic to the "L" (low-power) variant and is verified across the full military temperature range. The 7164L20TDB does not require external circuitry to enable this function.

Is the 7164L20TDB pin-compatible with the commercial-grade 7164S20TDB?

Yes - the 7164L20TDB and 7164S20TDB share identical pinout, package (28-pin SD28 CERDIP), and AC/DC electrical interface specifications. They differ only in standby current (5 µA vs. 2 mA) and data retention capability (2 V vs. none). This allows direct substitution in existing designs where enhanced power efficiency or battery backup is needed without PCB or firmware changes. The 7164L20TDB retains full functional equivalence in active mode.

What package type does the 7164L20TDB use, and why is it significant?

The 7164L20TDB uses a 28-pin 300-mil CERDIP (SD28) package - a hermetically sealed ceramic dual in-line package. This construction provides superior moisture resistance, thermal stability, and long-term reliability compared to plastic DIP or SOJ variants, making it mandatory for military and aerospace applications subject to MIL-STD-883 screening. The SD28 footprint ensures compatibility with legacy board layouts designed for high-reliability CERDIP memories. The 7164L20TDB's SD28 package is explicitly listed in Renesas' official ordering information.

How does chip select logic work on the 7164L20TDB?

The 7164L20TDB uses dual chip select inputs: CS1 (active-low) and CS2 (active-high). Both must be asserted simultaneously for normal read/write operation. Critically, CS2 has priority - if CS2 goes inactive (LOW), the device enters standby regardless of CS1 state. This hierarchical control enables robust power management in fault-tolerant systems. The 7164L20TDB truth table confirms that CS2-driven standby (ISB) occurs independently of CS1, supporting fail-safe low-power entry during system-level anomalies.