Renesas 71321SA35J

Overview

IDT71321SA35J from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM with on-chip interrupt logic and BUSY arbitration, designed as a MASTER device for interprocessor communication systems. It delivers 35 ns max read cycle time, operates on single 5V ±10% supply, supports industrial temperature range (–40°C to +85°C), and features two independent asynchronous ports with TTL-compatible I/O - used in real-time embedded control subsystems requiring concurrent CPU/DSP access to shared memory.

For engineers reviewing the IDT71321SA35J datasheet, IDT71321SA35J pinout, IDT71321SA35J application, or IDT71321SA35J equivalent, key selection considerations include its MASTER-only arbitration logic, open-drain BUSY output requiring 270Ω pull-up, interrupt mailbox addressing at 7FEh/7FFh, and compatibility with IDT71421SLAVE devices for 16-bit+ width expansion without external logic.

Technical Context

The IDT71321SA35J implements fully asynchronous dual-port architecture with separate address/control/I/O buses per port, enabling simultaneous read/write operations from left (L) and right (R) interfaces. Its on-chip arbitration logic evaluates CE and address match timing (tAPS = 5 ns min) to assert BUSYL/BUSYR outputs - open-drain flags that inhibit writes during contention.

Interrupt functionality uses dedicated mailboxes: INTL asserts when right port writes to address 7FEh; INTR asserts when left port writes to 7FFh. Both flags are cleared by reading the same address with OE active. The device lacks battery backup (LA variant only supports 2V data retention), confirming SA suffix denotes standard power version.

Key Specifications

Pinout & Package

Package: 52-pin STQFP (PPG52), body size 10 mm × 10 mm × 1.4 mm, lead pitch 0.5 mm, RoHS-compliant green package.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1371DV33 and IDT71421SA35J, the IDT71321SA35J uniquely combines 5V TTL compatibility, MASTER arbitration logic, and interrupt mailboxes - making it irreplaceable in legacy industrial and avionics systems requiring deterministic 5V dual-port memory without redesign.

Availability

IDT71321SA35J is available at Aetrix Electronics and suitable for real-time industrial PLCs, dual-CPU communication bridges, avionics data concentrators, and automated test equipment requiring stable component supply across extended product lifecycles.

Supply support for IDT71321SA35J 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 sensor solutions for communications, computing, and industrial markets.

IDT71321SA35J belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in hard real-time embedded systems where concurrent memory access and hardware arbitration are critical.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321SA35J?

BUSYL and BUSYR are open-drain arbitration outputs on the IDT71321SA35J that signal address contention between ports. When both ports attempt simultaneous access to the same memory location, the IDT71321SA35J asserts BUSYL or BUSYR (but never both) to inhibit writes on the losing port. External 270Ω pull-up resistors to VCC are mandatory for proper operation.

Can the IDT71321SA35J operate as a standalone dual-port RAM without a SLAVE device?

Yes, the IDT71321SA35J functions fully as a standalone 2K × 8 dual-port SRAM. Its MASTER arbitration logic operates internally - BUSY outputs manage contention between its own left and right ports. The SLAVE IDT71421 is optional and only required when expanding data bus width beyond 8 bits using MASTER/SLAVE topology.

How do the interrupt mailboxes work in the IDT71321SA35J?

The IDT71321SA35J uses fixed SRAM addresses for hardware interrupts: writing to 7FEh (hex) sets the left-port INTL flag; writing to 7FFh sets the right-port INTR flag. Reading either address with OE active clears the corresponding flag. These locations remain usable as general memory if interrupts are unused.

What is the difference between IDT71321SA35J and IDT71321LA35J?

IDT71321SA35J is the standard-power version (typ. 80 mA active current), while IDT71321LA35J is the low-power variant supporting 2V battery backup data retention. The SA suffix confirms absence of battery-retention capability - critical for systems where standby current <100 µA is not required.

Which package does the IDT71321SA35J use, and are there pin-compatible alternatives?

IDT71321SA35J is packaged in 52-pin STQFP (PPG52). Pin-compatible alternatives include the 52-pin PLCC (PLG52) and 64-pin TQFP (PNG64) variants - but these differ in footprint, thermal characteristics, and pin count. No drop-in replacement exists across packages; PCB layout must match PPG52 mechanical dimensions (10 mm × 10 mm, 0.5 mm pitch).