Renesas 71321SA25J

Overview

71321SA25J from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM with on-chip port arbitration and interrupt logic, designed as a MASTER device for interprocessor communication. It delivers 25 ns max access time (industrial grade), operates at 5V ±10%, supports fully asynchronous dual-port reads/writes, and features open-drain BUSY/INT outputs requiring 270Ω pull-up resistors - used in real-time embedded control systems requiring deterministic memory coherency.

For engineers reviewing the 71321SA25J datasheet, 71321SA25J pinout, 71321SA25J application, or 71321SA25J equivalent, key selection criteria include its MASTER arbitration capability, 2K × 8 dual-port architecture with independent CE/OE/R/W controls per port, industrial temperature range (–40°C to +85°C), and compatibility with IDT71421 SLAVE devices for 16-bit+ bus expansion.

Technical Context

The 71321SA25J implements hardware-based port arbitration using address and chip-enable timing (tAPS = 5 ns setup), asserting BUSYL/BUSYR outputs when both ports access the same address - blocking writes on the later-arriving port without software intervention. Its interrupt logic uses dedicated mailbox addresses (7FE_H for INTL, 7FF_H for INTR) with set/reset timing tINS/tINR ≤25 ns.

It supports two independent power domains: each port enters low-power standby (ISB1 = 30 mA typ.) when CE = VIH, and full CMOS-level standby (ISB3 = 1.0 mA typ.) when CE > VCC – 0.2 V. The device requires external 270Ω pull-ups on BUSY/INT pins and uses TTL-compatible 5V signaling with VIH ≥ 2.2 V and VOL ≤ 0.4 V.

Key Specifications

Pinout & Package

71321SA25J is packaged in a 52-pin STQFP (PPG52), measuring 10 mm × 10 mm × 1.4 mm, with exposed pad for thermal dissipation and standard surface-mount footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-25AXC and IDT71421SA25J, the 71321SA25J uniquely integrates MASTER arbitration and interrupt logic in a 2K × 8 footprint - enabling simpler, lower-latency dual-processor designs without external glue logic or dependency on companion parts.

Availability

71321SA25J is available at Aetrix Electronics and suitable for industrial PLC backplanes, real-time motor control interfaces, avionics data concentrators, and medical imaging subsystems requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for 71321SA25J 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 high-performance computing solutions.

The IDT71321 family was designed specifically for deterministic interprocessor communication in real-time embedded systems - delivering hardware-arbitrated dual-port SRAM with integrated interrupt and BUSY signaling to eliminate software coordination bottlenecks.

FAQ

What is the function of the BUSY pins on the 71321SA25J?

The BUSYL and BUSYR pins on the 71321SA25J are open-drain outputs that assert LOW when address contention occurs between ports - blocking writes on the later-arriving port. As a MASTER device, 71321SA25J generates BUSY signals; it does not accept them as inputs. External 270Ω pull-up resistors are mandatory per datasheet specification.

Can the 71321SA25J operate as a standalone dual-port RAM without a SLAVE device?

Yes, the 71321SA25J functions fully as a standalone 2K × 8 dual-port SRAM with independent left/right port access, arbitration, and interrupt capability. Its MASTER designation refers to its ability to drive BUSY outputs and coordinate with IDT71421 SLAVE devices - not a requirement for basic dual-port operation. No SLAVE is needed for single-device implementations.

How does the interrupt mechanism work in the 71321SA25J?

The 71321SA25J uses fixed mailbox addresses: writing to 7FE_H sets INTL (left interrupt), and writing to 7FF_H sets INTR (right interrupt). Reading those addresses clears the respective flag. Timing is guaranteed with tINS/tINR ≤25 ns. These locations remain usable as general RAM if interrupts are unused - no hardware reservation beyond flag behavior.

What power supply requirements does the 71321SA25J have?

The 71321SA25J requires a single 5.0 V ±10% supply (4.5 V to 5.5 V) with multiple VCC and GND pins that must all be connected. It draws 110 mA typical dynamic current (ICC) and 30 mA typical standby current (ISB1) at 25°C. No battery backup is supported - the LA variant offers 2V data retention, but 71321SA25J is the SA (standard power) version.

Is the 71321SA25J pin-compatible with other members of the IDT71321/71421 family?

Yes, the 71325J, 71321SA20J, and 71321SA35J share identical 52-pin STQFP (PPG52) pinout and signal mapping. Speed grades (20/25/35/55 ns) and variants (SA/LA) maintain mechanical and electrical compatibility - allowing drop-in replacement within the same package and temperature grade, provided timing margins are verified for the target clock frequency.