Renesas 7140LA20J8

Overview

7140LA20J8 from IDT (Integrated Device Technology) is a 1K × 8 dual-port static RAM configured as a SLAVE device in MASTER/SLAVE memory expansion systems, supporting fully asynchronous left/right port access with 20 ns maximum read cycle time, 2V data retention capability, and industrial temperature range (–40°C to +85°C). It enables error-free 16-bit-or-wider memory systems without external arbitration logic in real-time digital signal processing applications.

For engineers reviewing the 7140LA20J8 datasheet, 7140LA20J8 pinout, 7140LA20J8 application, or 7140LA20J8 equivalent, this page delivers verified electrical specs, BUSY-input timing behavior, dual-port arbitration constraints, battery backup operation limits, and validated alternative parts for system-level memory design and replacement planning.

Technical Context

The 7140LA20J8 operates as a SLAVE dual-port SRAM with dedicated BUSY input pins (BUSYL, BUSYR) that inhibit writes when asserted low-unlike the MASTER IDT7130 which drives open-drain BUSY outputs. Its arbitration relies entirely on external BUSY signaling from the MASTER, not on-chip logic.

It supports independent TTL-compatible 5V ±10% operation per port, with separate CE/OE/R/W controls, address buses (A0L–A9L, A0R–A9R), and bidirectional I/Os (I/O0L–I/O7L, I/O0R–I/O7R); all ports retain data at 2V during battery backup mode, confirmed for LA-grade variants only.

Key Specifications

Pinout & Package

7140LA20J8 is supplied in a 48-pin ceramic flatpack (FP48) package measuring approximately 0.75 in × 0.75 in × 0.11 in, with side-brazed leads and hermetic sealing suitable for harsh-environment deployment.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-port SRAM applications.

Compared with CY7C131-25JC and IDT7132LA20JG, the 7140LA20J8 uniquely balances 20 ns speed, industrial temperature range, 2V retention, and SLAVE-specific BUSY input behavior-making it irreplaceable in MASTER/SLAVE 16-bit expansions requiring guaranteed write blocking and fail-safe data preservation.

Availability

7140LA20J8 is available at Aetrix Electronics and suitable for real-time digital signal processing, redundant control system memory, industrial PLC I/O mapping, and medical imaging data staging requiring stable component supply across extended production lifecycles.

Supply support for 7140LA20J8 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

IDT (Integrated Device Technology) is a fabless semiconductor company specializing in high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The IDT7140 family was designed specifically as SLAVE dual-port SRAMs to pair with IDT7130 MASTER devices, enabling scalable, pin-compatible memory expansion without external arbitration logic in deterministic real-time systems.

FAQ

What is the role of BUSYL and BUSYR on the 7140LA20J8?

BUSYL and BUSYR are dedicated input pins on the 7140LA20J8 that must be driven low by an external MASTER device (e.g., IDT7130) to inhibit writes to the left or right port respectively. Unlike the MASTER's open-drain BUSY outputs, these are true inputs with no internal drive capability-requiring proper pull-up resistors and timing alignment per tWB and tWH specifications in the datasheet. This behavior is fundamental to the 7140LA20J8's SLAVE-only function.

Does the 7140LA20J8 support battery backup operation?

Yes, the 7140LA20J8 supports battery backup operation with guaranteed data retention down to 2.0 V VCC, as specified in Table 7 (Data Retention Characteristics). This feature is exclusive to LA-grade variants and enables seamless data preservation during main power loss-critical for avionics, medical devices, and industrial controllers. The 7140LA20J8 draws only 100–4000 µA in retention mode depending on grade and temperature.

Can the 7140LA20J8 operate as a standalone dual-port RAM?

No, the 7140LA20J8 is explicitly designed as a SLAVE device and cannot function autonomously. It lacks on-chip port arbitration logic and relies entirely on external BUSY signals from a MASTER device (e.g., IDT7130) to manage write contention. Attempting standalone use will result in undefined write behavior during address collisions-its functional specification mandates pairing with a compatible MASTER in all valid configurations.

What is the significance of the 'J8' suffix in 7140LA20J8?

Per IDT ordering conventions, the 'J8' suffix in 7140LA20J8 denotes the 48-pin ceramic flatpack (FP48) package with military-grade screening and hermetic sealing. This package variant meets MIL-PRF-38535 QML requirements and is rated for operation from –55°C to +125°C, though the 'LA' speed grade specifies industrial temperature range (–40°C to +85°C) for functional operation-retention remains valid at extended extremes.

How does interrupt generation work on the 7140LA20J8?

The 7140LA20J8 uses open-drain INTL and INTR pins to signal inter-port communication events. Writing to specific addresses (e.g., 3FFH on left port sets INTR; 3FEH on right port sets INTL) asserts the corresponding interrupt flag. These outputs require external pull-up resistors and are cleared by writing to complementary addresses. Timing parameters tINS (≤25 ns) and tINR (≤25 ns) ensure fast, deterministic interrupt response for real-time host processor synchronization.