Renesas 71321LA25PFI8

Overview

IDT71321LA25PFI8 from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM with interrupt logic and BUSY arbitration, designed as a MASTER device for interprocessor communication in real-time embedded systems. It delivers 25 ns max read cycle time, 2V data retention in battery backup mode, industrial temperature operation (–40°C to +85°C), and supports fully asynchronous dual-port access with independent control/address/I/O on left and right ports - used in multiprocessing memory bridges and real-time control subsystems.

For engineers reviewing the IDT71321LA25PFI8 datasheet, IDT71321LA25PFI8 pinout, IDT71321LA25PFI8 application, or IDT71321LA25PFI8 equivalent, key selection criteria include its MASTER arbitration capability, 2V data retention, 52-pin STQFP package compatibility, and interrupt mailbox addressing at 0x7FE/0x7FF - critical for deterministic inter-processor messaging in safety-critical industrial controllers.

Technical Context

The IDT71321LA25PFI8 implements on-chip port arbitration logic that resolves simultaneous accesses to identical addresses using CE and address match timing (tAPS = 5 ns), asserting BUSYL/BUSYR outputs to inhibit writes - no external logic required. Its interrupt system uses dedicated SRAM mailboxes (0x7FE for INTL, 0x7FF for INTR) with set/reset via port-specific write sequences, enabling lock-free message passing between CPUs.

As a low-power LA variant, it draws only 1 mA typical standby current (ISB3) at 5 V and retains data down to 2 V, making it suitable for battery-backed fail-safe memory buffers. All I/Os are TTL-compatible with 5 V ±10% supply, and both ports operate fully asynchronously with independent R/W, CE, OE, and address buses.

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 IDT71321SA25PFI8, the IDT71321LA25PFI8 enables battery backup operation and cuts standby power by 98%, while IDT71421LA25PFI8 serves exclusively as a SLAVE in multi-chip expansions - neither offers the standalone MASTER arbitration capability essential for dual-CPU memory coherency.

Availability

IDT71321LA25PFI8 is available at Aetrix Electronics and suitable for industrial PLC memory bridges, avionics data loggers, medical imaging control subsystems, automotive ADAS sensor fusion hubs, and medical diagnostic equipment requiring stable component supply across extended product lifecycles.

Supply support for IDT71321LA25PFI8 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, RF, and real-time interconnect solutions for communications, computing, and industrial markets.

The IDT71321LA25PFI8 belongs to IDT's legacy dual-port SRAM family engineered for deterministic interprocessor communication in hard real-time systems - emphasizing hardware arbitration, interrupt mailboxing, and battery-backed reliability over density or speed scaling.

FAQ

What is the function of the BUSY pins on the IDT71321LA25PFI8?

The BUSYL and BUSYR pins on the IDT71321LA25PFI8 are open-drain arbitration outputs that signal write inhibition when both ports attempt simultaneous access to the same memory address. As a MASTER device, IDT71321LA25PFI8 asserts BUSY to block conflicting writes - requiring external 270 Ω pull-up resistors per the datasheet. This hardware arbitration eliminates race conditions without software intervention.

Does the IDT71321LA25PFI8 support battery backup operation?

Yes, the IDT71321LA25PFI8 supports battery backup operation with guaranteed data retention down to 2 V VCC, a feature exclusive to LA variants. At 2 V and +25°C, it draws ≤1500 µA (typical) in retention mode. This enables seamless transition to backup power during main supply failure - critical for applications like flight data recorders and industrial safety controllers where data integrity must persist through brownouts.

How do the interrupt mailboxes work in the IDT71321LA25PFI8?

The IDT71321LA25PFI8 uses fixed SRAM addresses 0x7FE and 0x7FF as hardware interrupt mailboxes: writing to 0x7FE sets the INTL flag (left port), and writing to 0x7FF sets the INTR flag (right port). Clearing is performed by reading those addresses with CE and OE asserted. These are standard SRAM locations - the data written becomes the message payload, enabling lock-free, atomic inter-processor signaling without polling overhead.

Can the IDT71321LA25PFI8 be used as a standalone dual-port memory without a SLAVE device?

Yes, the IDT71321LA25PFI8 functions fully as a standalone 2K × 8 dual-port SRAM with complete left/right port independence, arbitration, and interrupt logic. Its MASTER designation means it contains on-chip arbitration and BUSY outputs - unlike SLAVE-only parts (e.g., IDT71421LA25PFI8) which require a MASTER to drive BUSY. No SLAVE device is needed unless expanding data bus width beyond 8 bits.

What package type is used for the IDT71321LA25PFI8?

The IDT71321LA25PFI8 uses a 52-pin STQFP package (PPG52), measuring 10 mm × 10 mm × 1.4 mm with exposed pad thermal enhancement. This surface-mount package supports automated assembly and provides robust thermal performance for industrial environments. Pinout matches the PLCC variant electrically but offers superior solder joint reliability and smaller footprint than through-hole alternatives.