Renesas 7140SA25J8

Overview

7140SA25J8 from IDT 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 25 ns maximum read cycle time, TTL-compatible 5V ±10% operation, and industrial temperature range (–40°C to +85°C). It serves as the slave unit in 16-bit-or-wider memory subsystems for real-time data exchange between independent processors or bus masters.

For engineers reviewing the 7140SA25J8 datasheet, 7140SA25J8 pinout, 7140SA25J8 application, or 7140SA25J8 equivalent, key selection criteria include BUSY input behavior (not output), absence of on-chip arbitration logic, compatibility with IDT7130SA25J8 master, and support for CE- or R/W-controlled write cycles in dual-processor interlock scenarios.

Technical Context

The 7140SA25J8 operates as a SLAVE dual-port SRAM with dedicated left (L) and right (R) ports, each featuring independent address (A0–A9), data (I/O0–I/O7), and control lines (CEL/CER, OEL/OER, R/WL/R/WR). Unlike the IDT7130, it lacks internal arbitration logic and uses BUSYL/BUSYR as inputs only - asserting low disables writes on the corresponding port during contention.

It supports two distinct write modes: CE-controlled (where CE transition initiates write) and R/W-controlled (where R/W transition initiates write), with timing parameters including tWC = 25 ns (max), tWP = 15 ns (min), and tBDD = 35 ns (max) for BUSY-disable-to-valid-data delay. Power management includes TTL-level standby (ISB1 = 30 mA typ.) and CMOS-level full standby (ISB3 = 1.0 mA typ.).

Key Specifications

Pinout & Package

7140SA25J8 is supplied in a 48-pin ceramic flatpack (FP48) package, body size ≈ 0.75 in × 0.75 in × 0.11 in, with solderable side-brazed leads and hermetic sealing per MIL-PRF-38535 QML requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C133-25JC and AS7C31025B-25JI, the 7140SA25J8 delivers purpose-built SLAVE functionality for IDT's MASTER/SLAVE architecture - preserving existing board layout and eliminating arbitration firmware, whereas alternatives demand interface redesign or compromise on real-time safety guarantees.

Availability

7140SA25J8 is available at Aetrix Electronics and suitable for real-time dual-processor systems, industrial motion controllers, and military communications equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 7140SA25J8 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 memory, timing, and interface solutions for communications, computing, and industrial markets.

The IDT7140 product line was designed specifically as SLAVE dual-port SRAMs to pair with IDT7130 MASTER devices, enabling scalable, low-latency, hardware-arbitrated memory expansion in deterministic embedded systems.

FAQ

What is the role of BUSYL and BUSYR on the 7140SA25J8?

On the 7140SA25J8, BUSYL and BUSYR are dedicated input-only signals - unlike the IDT7130 master, they do not drive output. When pulled low by an external master (e.g., IDT7130SA25J8), they inhibit writes on the respective port. The 7140SA25J8 does not generate BUSY; it responds to it. This design enforces hardware-level write blocking during address contention without software intervention.

Can the 7140SA25J8 operate standalone without an IDT7130 master?

Yes, the 7140SA25J8 can operate as a standalone dual-port SRAM with independent left and right port access. However, its BUSY inputs will remain unconnected (pulled high), disabling hardware contention resolution. In this mode, the 7140SA25J8 functions like a basic dual-port RAM - useful for simple dual-CPU sharing where software manages arbitration, but losing the key advantage of automatic write inhibition provided in MASTER/SLAVE configurations.

What does the 'J8' suffix indicate in 7140SA25J8?

'J8' denotes a 48-pin ceramic flatpack package compliant with MIL-PRF-38535 QML Class V requirements. It specifies hermetic sealing, side-brazed leads, and qualification for military temperature range (–55°C to +125°C), though the 'SA' speed grade (25 ns) is rated for industrial operation (–40°C to +85°C). The J8 package ensures long-term reliability in harsh environments such as aerospace and defense platforms.

How does interrupt generation work on the 7140SA25J8?

The 7140SA25J8 supports hardware interrupts via INTL and INTR pins, which are open-drain outputs. Writing to address 3FFH on one port asserts the interrupt flag on the opposite port (e.g., writing 3FFH to left port sets INTR). Similarly, writing 3FEH clears the opposite flag. These signals require external pull-up resistors and enable low-latency, lock-free inter-processor signaling - critical for time-sensitive embedded coordination without polling overhead.

Is the 7140SA25J8 pin-compatible with other IDT7140 variants like 7140LA25J8?

Yes, the 7140SA25J8 is pin-compatible with all IDT7140 variants in the same package (e.g., 7140LA25J8), sharing identical pinout, voltage levels, and timing interface. The difference lies in power characteristics: 'SA' denotes standard active/standby current (550 mW active, 5 mW standby), while 'LA' offers lower standby (1 mW) and battery backup retention at 2V - but LA versions are not qualified for the same industrial temperature range as SA. Electrical and mechanical compatibility is maintained.