Renesas 71321LA35J8

Overview

IDT71321LA35J8 from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM with interrupt and BUSY arbitration logic, designed as a MASTER device for interprocessor communication in real-time embedded systems. It delivers 35 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 left/right control, address, and I/O buses. It is used in redundant controller architectures requiring deterministic port-to-port handshaking.

For engineers reviewing the IDT71321LA35J8 datasheet, IDT71321LA35J8 pinout, IDT71321LA35J8 application, or IDT71321LA35J8 equivalent, key selection criteria include BUSY arbitration timing (tBAA ≤ 30 ns), interrupt mailbox addressing (7FEh/7FFh), low-power standby current (1 µA typical full standby), and compatibility with 52-pin STQFP packaging for space-constrained industrial PCBs.

Technical Context

The IDT71321LA35J8 implements on-chip port arbitration logic that resolves simultaneous accesses to identical memory addresses using chip enable and address match detection - not R/W state - generating BUSY flags to inhibit conflicting writes. Its interrupt subsystem uses dedicated mailbox addresses (7FEh for INTL, 7FFh for INTR) with set/reset semantics controlled by write cycles on the opposite port.

As a MASTER-only device, it features open-drain BUSYL/BUSYR outputs requiring 270 Ω pull-up resistors, while supporting TTL-compatible 5 V ±10% supply and CMOS-level standby control. The LA variant enables 2 V battery backup with 100–1500 µA retention current, distinguishing it from SA versions.

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-35AXC and IDT71421LA35J8, the IDT71321LA35J8 uniquely integrates MASTER arbitration and interrupt mailboxes in a single 2K × 8 device, enabling simpler, lower-latency interprocessor communication without external components or pairing constraints.

Availability

IDT71321LA35J8 is available at Aetrix Electronics and suitable for redundant controller systems, real-time industrial PLCs, and avionics data concentrators requiring stable component supply, long-term lifecycle support, and industrial-grade reliability.

Supply support for IDT71321LA35J8 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 power solutions for communications and industrial markets.

The IDT71321LA35J8 belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in safety-critical and real-time embedded systems requiring hardware-enforced arbitration and low-power retention.

FAQ

What is the function of the BUSY pins on the IDT71321LA35J8?

The BUSYL and BUSYR pins on the IDT71321LA35J8 are open-drain outputs that assert low when address contention is detected between left and right ports - indicating that a write operation on the contending port must be inhibited. These signals require 270 Ω pull-up resistors per the datasheet and are used for hardware-level arbitration without software intervention. As a MASTER device, IDT71321LA35J8 generates BUSY; SLAVE devices like IDT71421LA35J8 accept BUSY as an input.

Does the IDT71321LA35J8 support battery backup operation?

Yes, the IDT71321LA35J8 supports battery backup operation with guaranteed data retention at VCC = 2.0 V, consuming 100–1500 µA depending on temperature. This capability is exclusive to LA variants and enables nonvolatile storage during main power loss - critical for avionics, medical, and industrial control applications. The SA version does not support this feature.

How are interrupts implemented in the IDT71321LA35J8?

Interrupts in the IDT71321LA35J8 use dedicated SRAM mailbox addresses: writing to 7FEh (hex) from the right port asserts INTL, and writing to 7FFh from the left port asserts INTR. Each flag is cleared by reading the same address with OE enabled. These are hardware-generated, edge-triggered signals with tINS ≤ 25 ns and tINR ≤ 45 ns timing, enabling fast interprocessor signaling without polling overhead.

What package type is used for the IDT71321LA35J8?

The IDT71321LA35J8 is packaged in a 52-pin STQFP (PPG52) with dimensions 10 mm × 10 mm × 1.4 mm. This lead-free, RoHS-compliant package features an exposed thermal pad and is optimized for automated assembly and thermal performance in dense industrial PCB layouts. It is distinct from the 64-pin TQFP variants used for other speed grades or SA versions.

Can the IDT71321LA35J8 operate in a standalone configuration?

Yes, the IDT71321LA35J8 functions as a complete standalone 2K × 8 dual-port SRAM with full MASTER arbitration, interrupt generation, and BUSY signaling. It does not require a companion SLAVE device unless expanding data bus width beyond 8 bits. In contrast, IDT71421LA35J8 is SLAVE-only and cannot operate independently - it relies on a MASTER like IDT71321LA35J8 for arbitration.