Renesas 71321LA25JI

Overview

IDT71321LA25JI 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 - confirmed for LA variant.

For engineers reviewing the 71321LA25JI datasheet, 71321LA25JI pinout, 71321LA25JI application, or 71321LA25JI equivalent, key selection criteria include dual-port asynchronous read/write capability, on-chip port arbitration, interrupt flag generation via mailbox addresses (7FEh/7FFh), and compatibility with IDT71421SLAVE devices for 16-bit+ bus expansion.

Technical Context

The 71321LA25JI implements fully independent left/right ports with separate address, control, and I/O buses, enabling concurrent access without external synchronization. Its internal arbitration logic uses chip enable (CE) and address match detection to assert open-drain BUSY outputs - requiring 270Ω pull-up resistors - to prevent write contention.

Interrupt functionality is implemented via dedicated mailbox addresses: writing to 7FEh sets INTL, reading it clears it; writing to 7FFh sets INTR, reading it clears it. The LA suffix confirms low-power operation with 1 µA typical standby current and 2V data retention - a feature absent in SA variants.

Key Specifications

Pinout & Package

71321LA25JI is packaged in a 52-pin STQFP (PPG52), measuring 10 mm × 10 mm × 1.4 mm, with exposed thermal pad and lead-free RoHS-compliant finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-25AXC and IDT71421LA25JI, the 71321LA25JI uniquely integrates MASTER arbitration, 5V operation, and 2V data retention - making it irreplaceable in legacy industrial 5V dual-processor designs requiring hardware-enforced coherency and battery backup.

Availability

71321LA25JI is available at Aetrix Electronics and suitable for industrial automation, avionics data buffering, and redundant control system memory requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 71321LA25JI 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.

The IDT71321 family was engineered specifically for deterministic interprocessor communication in real-time embedded systems - emphasizing hardware arbitration, low-latency dual-port access, and industrial reliability over general-purpose SRAM features.

FAQ

What is the function of BUSYL and BUSYR on the 71321LA25JI?

BUSYL and BUSYR are open-drain output signals on the 71321LA25JI that indicate write contention when both ports attempt simultaneous access to the same memory location. They require external 270Ω pull-up resistors per datasheet Figure 3. When asserted (pulled low), they inhibit writes on the respective port - a core part of the on-chip arbitration logic unique to the MASTER 71321LA25JI.

Does the 71321LA25JI support battery backup operation?

Yes, the 71321LA25JI supports battery backup operation with guaranteed data retention at 2.0 V, as specified in Table 06 of the datasheet. This is a defining feature of the LA (low-power) variant - the SA version does not provide this capability. Retention current is ≤1500 µA at +25°C, enabling long-term hold with small coin-cell batteries.

How do the interrupt flags INTL and INTR work on the 71321LA25JI?

INTL and INTR are open-drain interrupt flags triggered by writes to dedicated mailbox addresses: writing to 7FEh (hex) asserts INTL, and writing to 7FFh asserts INTR. Each flag is cleared by reading its respective address. These functions are implemented in hardware and require no firmware polling - enabling event-driven interprocessor communication with sub-25 ns latency as confirmed in Table 11a.

Can the 71321LA25JI be used without a companion SLAVE device?

Yes, the 71321LA25JI operates as a fully functional stand-alone 8-bit dual-port SRAM. Its MASTER designation refers to its ability to drive BUSY outputs and manage arbitration - not a dependency on a SLAVE. The IDT71421 is only required when expanding data bus width beyond 8 bits (e.g., 16-bit systems), per the functional description on page 2 of the datasheet.

What package type is used for the 71321LA25JI?

The 71321LA25JI uses a 52-pin STQFP package designated PPG52, with dimensions of 10 mm × 10 mm × 1.4 mm and a lead-free, RoHS-compliant finish. Pin configuration matches the top-view diagram in Figure 03a of the datasheet, including dedicated VCC/GND pairs and NC pins at positions 21, 22, 33, 45, 46, 51, and 52.