Renesas 71321SA45J

Overview

IDT71321SA45J 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 supports 45 ns max access time, operates at 5 V ±10%, delivers 2K × 8 (16 Kbit) memory density, and features two independent asynchronous ports with BUSY output and INTL/INTR flags - used in real-time embedded control systems requiring concurrent CPU/DSP access to shared memory.

For engineers reviewing the IDT71321SA45J datasheet, IDT71321SA45J pinout, IDT71321SA45J application, or IDT71321SA45J equivalent, key selection criteria include its 45 ns read cycle time, MASTER-only arbitration logic, open-drain BUSYL/INTL outputs requiring 270 Ω pull-ups, industrial temperature support (–40°C to +85°C), and compatibility with 52-pin STQFP packaging.

Technical Context

The IDT71321SA45J implements fully asynchronous dual-port architecture with separate address, control, and I/O buses per port - enabling simultaneous read/write operations without internal contention detection on the same port. Its arbitration logic responds exclusively to chip enable (CEL/CER) and address match (A0–A10) timing, not R/W state, and asserts BUSY only during cross-port address collisions.

As a MASTER-only device, it integrates BUSY output logic (open-drain, requires external 270 Ω pull-up), interrupt flag generation (INTL set by right-port write to 7FEh, INTR set by left-port write to 7FFh), and automatic power-down via CE control - delivering 5 mW typical standby power in SA variant at 5 V.

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-45AXC and IS61LV25616AL-10TLI, the IDT71321SA45J uniquely delivers hardware-enforced port arbitration and interrupt mailboxing in a 2K × 8 footprint - making it irreplaceable in real-time systems where deterministic sub-50 ns interprocessor coordination is mandatory.

Availability

IDT71321SA45J is available at Aetrix Electronics and suitable for real-time motor control, avionics data acquisition, and industrial PLC I/O mapping requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for IDT71321SA45J 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 high-performance computing and communications infrastructure.

The IDT71321SA/LA family was engineered specifically for deterministic interprocessor communication in hard real-time embedded systems - emphasizing low-latency arbitration, interrupt-driven messaging, and industrial reliability over raw density or speed.

FAQ

What is the function of the BUSYL pin on the IDT71321SA45J?

The BUSYL pin on the IDT71321SA45J is an open-drain output that signals address contention on the left port. When the right port accesses the same memory location simultaneously, BUSYL is driven low (requiring a 270 Ω pull-up to VCC) to inhibit writes on the left port. This hardware arbitration ensures data integrity without software intervention and is active only in MASTER configuration - a defining feature of the IDT71321SA45J.

Can the IDT71321SA45J operate in battery backup mode?

No, the IDT71321SA45J cannot operate in battery backup mode. Battery backup with 2 V data retention is exclusive to LA variants (e.g., IDT71321LA45J). The 'SA' suffix denotes standard power consumption (5 mW standby), while 'LA' indicates low-power design optimized for backup operation. Using IDT71321SA45J in a 2 V backup circuit will result in undefined data retention behavior and is outside its specified operating conditions.

How does interrupt generation work in the IDT71321SA45J?

In the IDT71321SA45J, interrupt generation is hardware-triggered by writes to fixed mailbox addresses: a write to 7FEh (hex) by the right port asserts the open-drain INTL flag, and a write to 7FFh by the left port asserts INTR. Both flags remain active until cleared by a read access to the same address with OE enabled. This zero-software-overhead mechanism enables sub-25 ns interprocessor signaling - a core capability confirmed in the IDT71321SA45J datasheet timing tables.

Is the IDT71321SA45J pin-compatible with IDT71421 devices?

No, the IDT71321SA45J is not pin-compatible with IDT71421 devices. Although both share identical pin counts and package footprints (e.g., 52-pin STQFP), their BUSY pin roles differ fundamentally: IDT71321SA45J has BUSYL as output and BUSYR as input, whereas IDT71421 reverses these roles (BUSYL input, BUSYR output). Swapping them without board redesign will cause functional failure - confirming that IDT71321SA45J is MASTER-only and not a drop-in replacement for SLAVE variants.

What is the maximum junction temperature for continuous operation of the IDT71321SA45J?

The IDT71321SA45J is rated for continuous operation up to +125°C junction temperature (T_J), as specified in its Absolute Maximum Ratings table. However, its guaranteed functional performance - including 45 ns access time and full electrical specifications - is validated only over the industrial ambient temperature range of –40°C to +85°C. Operation beyond +85°C ambient requires derating analysis and is not supported by production test data for the IDT71321SA45J.