Renesas 7140SA55J

Overview

7140SA55J 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 55 ns max read/write cycle time, TTL-compatible 5V ±10% supply, and industrial temperature range (–40°C to +85°C) - used in real-time DSP co-processing and shared-memory inter-processor communication.

For engineers reviewing the 7140SA55J datasheet, 7140SA55J pinout, 7140SA55J application, or 7140SA55J equivalent, this page delivers verified timing parameters, BUSY input behavior, CE/R/W-controlled write constraints, and SLAVE-specific arbitration interface details required for deterministic dual-port memory system design.

Technical Context

The 7140SA55J operates as a SLAVE unit paired with IDT7130 MASTER, accepting BUSY input signals (BUSYL/BUSYR) to inhibit writes during address contention; it lacks on-chip arbitration logic and relies entirely on external BUSY assertion from the MASTER device.

Its dual independent ports support simultaneous read/write operations only when non-conflicting addresses are accessed; port-to-port data visibility delay (tDDD = 30 ns min, 35 ns max) and write pulse-to-data delay (tWDD = 40 ns min, 60 ns max) are defined under controlled timing conditions per AC Table 11a.

Key Specifications

Pinout & Package

7140SA55J is supplied in a 48-pin ceramic flatpack (FP48) package measuring approximately 0.75 in × 0.75 in × 0.11 in, with 2×24 pin grid, gull-wing leads, and hermetic sealing suitable for industrial environments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C135-55JC and IDT7132SA55J, the 7140SA55J uniquely delivers SLAVE-specific BUSY input behavior and guaranteed timing compatibility within IDT's MASTER/SLAVE expansion architecture - critical for maintaining deterministic arbitration in legacy designs.

Availability

7140SA55J is available at Aetrix Electronics and suitable for industrial PLCs, real-time DSP subsystems, redundant control modules, and legacy bus bridge interfaces requiring stable component supply across extended product lifecycles.

Supply support for 7140SA55J 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 semiconductor company specializing in timing, memory interface, RF, and sensor solutions, acquired by Renesas Electronics in 2019.

The IDT7130/7140 product line was engineered specifically for deterministic, low-latency shared-memory inter-processor communication in industrial and military embedded systems - emphasizing bus contention resolution and timing predictability over density or power efficiency.

FAQ

What is the role of BUSYL and BUSYR on the 7140SA55J?

On the 7140SA55J, BUSYL and BUSYR are dedicated input-only signals - unlike the IDT7130 MASTER, they do not drive output. When pulled LOW by the MASTER device, they internally inhibit write operations to the corresponding port. This behavior is fundamental to the SLAVE function and is documented in Truth Table III and AC Table 11a.

Does the 7140SA55J support battery backup or data retention below 5V?

No, the 7140SA55J does not support battery backup or low-voltage data retention. That capability is exclusive to the LA variant (e.g., 7140LA55J), which specifies VDR = 2.0 V and ICCDR ≤ 4000 µA. The "SA" suffix explicitly denotes standard active-power operation with no retention mode.

Can the 7140SA55J be used without an IDT7130 MASTER device?

Yes, but only in non-contention configurations where both ports access disjoint address ranges and external arbitration is implemented. The 7140SA55J lacks on-chip arbitration logic and BUSY output capability - so deterministic conflict resolution requires either a MASTER device or discrete logic, as stated in the Functional Block Diagram notes.

What is the meaning of "55" in the part number 7140SA55J?

The "55" in 7140SA55J specifies the maximum access time rating: 55 ns for read cycle time (tRC), address access (tAA), and chip enable access (tACE). This speed grade applies across commercial, industrial, and military temperature ranges per AC Table 09b, and is validated under VCC = 5.0 V ±10% and TA = +25°C typical conditions.

How does interrupt flag operation differ between the left and right ports of the 7140SA55J?

INTL and INTR are functionally identical open-drain outputs. Setting or clearing either flag requires writing specific address patterns (e.g., A9–A0 = 3FFh to set INTR, 3FEh to set INTL) as defined in Truth Table II. Both flags operate independently, and their timing (tINS = 25 ns max, tINR = 25 ns max) is identical per AC Table 12a - no asymmetry exists between ports.