Renesas 71321LA25JI8

Overview

IDT71321LA25JI8 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 25 ns max access time, operates on single 5V ±10% supply, supports industrial temperature (–40°C to +85°C), and enables battery-backed data retention at 2V - used in dual-CPU arbitration, shared-memory IPC, and real-time control buffers.

For engineers reviewing the IDT71321LA25JI8 datasheet, IDT71321LA25JI8 pinout, IDT71321LA25JI8 application, or IDT71321LA25JI8 equivalent, key selection criteria include its MASTER-only BUSY output behavior, dual-interrupt mailbox addressing (7FEh/7FFh), 52-pin STQFP package, 2V data retention capability, and compatibility with IDT71421LA SLAVE devices in 16-bit+ memory expansion.

Technical Context

The IDT71321LA25JI8 implements fully asynchronous dual-port operation with independent left/right address, control, and I/O buses. Its on-chip arbitration logic uses chip enable (CEL/CER) and address match detection (A0–A10) - not R/W state - to assert open-drain BUSYL/BUSYR outputs within 20 ns, blocking concurrent writes to identical addresses.

Interrupt functionality relies on dedicated mailbox addresses: INTL asserts when right port writes to 7FEh; INTR asserts when left port writes to 7FFh. Both flags are cleared by read-access to their respective addresses with OE enabled - no external logic required for basic inter-processor signaling.

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 IDT71321LA25JI8, CY7C1371DV33-250BZI offers higher bandwidth but lacks integrated arbitration and 2V retention, while IDT71421LA25JI8 provides identical low-power operation but cannot function autonomously as a MASTER - both require architectural changes to replace IDT71321LA25JI8 in existing designs.

Availability

IDT71321LA25JI8 is available at Aetrix Electronics and suitable for real-time dual-CPU control, avionics redundancy systems, industrial PLC co-processor buffering, and medical imaging pipelines requiring stable component supply across extended production lifecycles.

Supply support for IDT71321LA25JI8 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.

IDT71321LA25JI8 belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in safety-critical and low-latency embedded systems - emphasizing hardware arbitration, interrupt efficiency, and robust data retention.

FAQ

What is the primary functional distinction between IDT71321LA25JI8 and IDT71421LA25JI8?

IDT71321LA25JI8 is a MASTER dual-port SRAM with on-chip arbitration logic and open-drain BUSY outputs, enabling autonomous conflict detection and resolution. IDT71421LA25JI8 is a SLAVE device with BUSY inputs only and no arbitration - it relies entirely on the MASTER's BUSY signal to inhibit writes. The IDT71321LA25JI8 can operate stand-alone; IDT71421LA25JI8 requires pairing with a MASTER like IDT71321LA25JI8 in width-expanded systems.

Does IDT71321LA25JI8 support true simultaneous read/write operations across ports?

Yes - IDT71321LA25JI8 supports fully asynchronous dual-port operation: left and right ports may perform independent reads or writes concurrently. However, when both ports access the same memory address, hardware arbitration asserts BUSYL/BUSYR within 20 ns to block the later-initiated write, ensuring data integrity without software intervention.

How is the 2V data retention capability of IDT71321LA25JI8 implemented and verified?

IDT71321LA25JI8 achieves 2V data retention through optimized CMOS design and process tuning specific to the LA (low-power) variant. Per datasheet Table 6, VDR = 2.0 V min is guaranteed (not production-tested), with ICCDR ≤ 1500 µA at TA = +25°C. Retention is validated under static conditions (CE > VCC − 0.2 V, no address transitions) - dynamic operation below 4.5 V is not supported.

What are the exact pin requirements for BUSY and INT signals on IDT71321LA25JI8?

IDT71321LA25JI8's BUSYL, BUSYR, INTL, and INTR pins are open-drain outputs requiring external 270 Ω pull-up resistors to VCC, as specified in datasheet Note 2 and Figure 3. Driving these pins directly high or leaving them unconnected violates electrical specifications and may cause arbitration failure or false interrupt assertion.

Can IDT71321LA25JI8 be used without enabling the interrupt or BUSY features?

Yes - IDT71321LA25JI8 operates as a standard dual-port SRAM when interrupts and BUSY logic are unused. INTL/INTR pins default to high-impedance (pulled high externally), and BUSYL/BUSYR remain inactive (high) unless address conflicts occur. Address locations 7FEh and 7FFh function as regular memory unless explicitly used for mailbox signaling.