Renesas 71321SA55JI

Overview

IDT71321SA55JI 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 at 5 V ±10%, supports industrial temperature range (–40°C to +85°C), and features open-drain BUSY/INT outputs requiring 270 Ω pull-up resistors - used in real-time embedded control systems requiring concurrent memory access.

For engineers reviewing the IDT71321SA55JI datasheet, IDT71321SA55JI pinout, IDT71321SA55JI application, or IDT71321SA55JI equivalent, key selection criteria include dual-port arbitration timing (tAPS = 5 ns), BUSY output behavior (open-drain, tBAA ≤ 30 ns), interrupt mailbox addressing (7FEH/7FFH), and compatibility with IDT71421SLAVE expansion in 16-bit+ systems.

Technical Context

The IDT71321SA55JI implements fully asynchronous dual-port operation with independent left/right address, control, and I/O buses. Its on-chip arbitration logic resolves port contention using chip-enable and address-match detection - not R/W state - and asserts BUSYL/BUSYR outputs to inhibit writes during conflict.

Interrupt functionality uses dedicated SRAM addresses (7FEH for INTL, 7FFH for INTR) to signal cross-port events; assertion occurs on write, clearance on read. The device supports battery backup data retention only in LA variants - not applicable to this SA-grade part.

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 CY7C136-55JC, IDT71321SA55JI reduces BOM count and PCB area by integrating arbitration and interrupts; compared with IDT71421SA55JI, it enables autonomous master functionality without dependency on external coordination logic.

Availability

IDT71321SA55JI is available at Aetrix Electronics and suitable for real-time dual-core control, industrial PLC memory buffering, and avionics data logger interfaces requiring stable component supply across extended product lifecycles.

Supply support for IDT71321SA55JI 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, specializes in high-performance timing, memory interface, and RF solutions for communications and computing infrastructure.

IDT71321SA55JI belongs to the IDT71321/71421 dual-port SRAM family, engineered specifically for deterministic interprocessor communication in hard real-time embedded systems where hardware arbitration eliminates software synchronization bottlenecks.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321SA55JI?

BUSYL and BUSYR are open-drain output signals indicating port contention on the left and right ports respectively. When asserted (pulled low), they inhibit writes to the corresponding port during address matches. Each requires an external 270 Ω pull-up resistor to VCC. These signals are outputs only on IDT71321SA55JI and are used to drive BUSY inputs on IDT71421SLAVE devices in width-expanded systems.

Does the IDT71321SA55JI support battery backup data retention?

No, the IDT71321SA55JI does not support battery backup data retention. That feature is exclusive to LA-grade variants (e.g., IDT71321LA55JI), which guarantee data retention at 2.0 V. The 'SA' suffix denotes standard active-power operation only, with full functionality at 5.0 V ±10% and no low-voltage retention capability.

How do the interrupt mailboxes work in the IDT71321SA55JI?

The IDT71321SA55JI uses SRAM addresses 7FEH (hex) and 7FFH to implement hardware interrupts: a write to 7FEH by the right port sets INTL; a write to 7FFH by the left port sets INTR. Clearing occurs when the respective port reads that address. Both INTL and INTR are open-drain outputs requiring 270 Ω pull-ups, and their assertion latency is ≤45 ns per the datasheet.

Can the IDT71321SA55JI operate as a standalone dual-port RAM without a SLAVE device?

Yes, the IDT71321SA55JI functions fully as a standalone 2K × 8 dual-port SRAM. Its on-chip arbitration, BUSY outputs, and interrupt logic operate independently. The SLAVE pairing (IDT71421) is optional and used only when expanding data bus width beyond 8 bits - for example, combining one IDT71321SA55JI MASTER with multiple IDT71421SA55JI SLAVES to build a 16-bit or wider memory system.

What is the significance of the '55' in IDT71321SA55JI?

The '55' in IDT71321SA55JI specifies the maximum read cycle time rating: 55 ns. This defines the device's speed grade and correlates directly to timing parameters including tRC, tAA, tACE, and tAOE. It also implies qualification for industrial temperature range (–40°C to +85°C) and compatibility with 55 ns versions of companion SLAVE parts like IDT71421SA55JI.