Renesas 71321SA55J

Overview

IDT71321SA55J from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM with interrupt logic and on-chip arbitration, designed as a MASTER device for interprocessor communication. It delivers 55 ns max read cycle time, operates on single 5V ±10% supply, supports industrial temperature range (–40°C to +85°C), and features open-drain BUSY/INT outputs requiring 270Ω pull-up resistors - used in real-time embedded control systems requiring concurrent memory access.

For engineers reviewing the IDT71321SA55J datasheet, IDT71321SA55J pinout, IDT71321SA55J application, or IDT71321SA55J equivalent, key selection criteria include its MASTER arbitration capability, 55 ns timing grade, 52-pin STQFP package, dual-interrupt mailbox addressing (7FEh/7FFh), and compatibility with IDT71421SLAVE devices in 16-bit+ bus expansion.

Technical Context

The IDT71321SA55J implements fully asynchronous dual-port architecture with independent left/right address, control, and I/O buses. Its on-chip arbitration logic resolves port contention via BUSY flag generation based on chip enable and address match timing - not R/W state - enabling deterministic write inhibition during simultaneous access to identical addresses.

As a MASTER-only device, it provides BUSYL/BUSYR as open-drain outputs (requiring external 270Ω pull-ups) and includes dedicated INTL/INTR flags triggered by writes to fixed mailbox addresses (7FEh and 7FFh). It does not accept BUSY as input - that function is reserved for SLAVE IDT71421 variants.

Key Specifications

Pinout & Package

Package: 52-pin STQFP (PPG52), 10 mm × 10 mm × 1.4 mm body, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-55AXC and IDT71421SA55J, the IDT71321SA55J uniquely integrates MASTER arbitration and dual-interrupt mailboxes in a 55 ns 2K × 8 footprint - making it irreplaceable for compact, low-latency interprocessor communication where hardware-coordinated access and event signaling are mandatory.

Availability

IDT71321SA55J is available at Aetrix Electronics and suitable for real-time dual-CPU communication, motor control co-processor interfaces, and PLC I/O data exchange requiring stable component supply and long-term industrial lifecycle support.

Supply support for IDT71321SA55J 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

Integrated Device Technology (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, and RF solutions for communications and industrial markets.

The IDT71321 family was engineered specifically for deterministic interprocessor communication in embedded control systems - prioritizing hardware arbitration, interrupt signaling, and industrial temperature reliability over density or power efficiency.

FAQ

What is the function of the BUSY pins on the IDT71321SA55J?

The BUSYL and BUSYR pins on the IDT71321SA55J are open-drain outputs that assert low when the opposite port attempts to access the same memory address - indicating contention. This signal must be pulled up with a 270Ω resistor and is used to inhibit writes on the contending port. Unlike SLAVE devices, IDT71321SA55J never accepts BUSY as an input; it generates BUSY exclusively as a MASTER.

Can the IDT71321SA55J operate as a standalone dual-port RAM without a SLAVE device?

Yes, the IDT71321SA55J functions fully as a standalone 2K × 8 dual-port SRAM with all features active - including arbitration, interrupts, and both BUSY outputs. Its SLAVE counterpart (IDT71421) is optional and only needed when expanding data bus width beyond 8 bits. The IDT71321SA55J does not require any companion device to operate correctly in single-chip configurations.

How are the interrupt flags INTL and INTR triggered on the IDT71321SA55J?

INTL is asserted low when the right port writes to address 7FEh (hex); INTR is asserted low when the left port writes to address 7FFh (hex). Both flags remain active until cleared by a read access to the same address with OE and CE enabled. These are hardware-generated signals - no firmware polling or register writes are needed to set or clear them on the IDT71321SA55J.

What package type is used for the IDT71321SA55J, and are there pin-compatible alternatives in other packages?

The IDT71321SA55J uses a 52-pin STQFP (PPG52) package measuring 10 mm × 10 mm × 1.4 mm. While the same speed grade is offered in 52-pin PLCC (PLG52) and 64-pin TQFP (PNG64), these are not pin-compatible - the PPG52 pinout is unique to the STQFP variant. No direct pin-to-pin alternative exists across packages; board layout must match the specific PPG52 footprint.

Does the IDT71321SA55J support battery backup data retention like some LA-series variants?

No, the IDT71321SA55J is an SA-series device and does not support battery backup data retention. Only LA-series variants (e.g., IDT71321LA55J) provide 2V data retention capability. The SA suffix indicates standard power consumption (325 mW typical active, 5 mW typical standby) without low-voltage retention circuitry - confirming IDT71321SA55J is intended for main-supply-powered industrial applications.