Renesas 71V321L55JI8

Overview

71V321L55JI8 from Renesas Electronics is a high-speed 3.3V 2K × 8 dual-port static RAM with on-chip interrupt logic and BUSY arbitration, designed for interprocessor communication in real-time embedded systems. It delivers 55 ns read/write cycle time, 2V battery-backed data retention, and operates across –40°C to +85°C industrial temperature range in a 52-pin PLCC package.

For engineers reviewing the 71V321L55JI8 datasheet, 71V321L55JI8 pinout, 71V321L55JI8 application, or 71V321L55JI8 equivalent, this page provides verified technical context, exact pin functions, real-world use cases in multiprocessing systems, and validated alternative parts for design continuity and supply resilience.

Technical Context

The 71V321L55JI8 implements fully asynchronous dual-port architecture with independent left/right control, address, and I/O buses-enabling concurrent read/write access without external synchronization. Its on-chip arbitration logic uses address and chip-enable matching (not R/W state) to assert BUSYL/BUSYR outputs, preventing simultaneous writes to identical memory locations.

Interrupt functionality is implemented via dedicated mailbox addresses: INTL asserts when right port writes to 0x7FE; INTR asserts when left port writes to 0x7FF. Both flags are active-high totem-pole outputs, requiring no pull-ups, and support software-triggered inter-processor signaling without polling overhead.

Key Specifications

Pinout & Package

71V321L55JI8 is housed in a 52-pin Plastic Leaded Chip Carrier (PLCC, package code PLG52), with leads arranged in a square J-lead configuration. The package body measures approximately 19.05 mm × 19.05 mm × 4.32 mm (0.75 in × 0.75 in × 0.17 in).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-55AXC and AS7C3256B-55JCIN, the 71V321L55JI8 uniquely integrates BUSY arbitration and dual interrupt flags in a compact 52-pin PLCC, enabling drop-in replacement in legacy dual-CPU designs without logic or layout changes - a critical advantage for industrial lifecycle continuity.

Availability

71V321L55JI8 is available at Aetrix Electronics and suitable for industrial PLCs, avionics data exchange, medical imaging subsystems, real-time motor control, and redundant computing systems requiring stable component supply across extended product lifecycles.

Supply support for 71V321L55JI8 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

Renesas Electronics Corporation is a global semiconductor leader delivering microcontrollers, analog, power, and connectivity solutions for automotive, industrial, infrastructure, and IoT applications.

The 71V321L55JI8 belongs to Renesas' legacy dual-port SRAM product line, engineered specifically for deterministic, low-latency interprocessor communication in mission-critical embedded systems where hardware arbitration and interrupt signaling eliminate software bottlenecks.

FAQ

What is the maximum operating speed of the 71V321L55JI8?

The 71V321L55JI8 is rated for a 55 ns read/write cycle time (tRC and tWC), meaning it supports up to ~18.2 MHz sustained memory access under commercial and industrial temperature conditions. This speed is guaranteed across its full operating range of –40°C to +85°C with 3.3 V ± 0.3 V supply, and applies to both left and right ports independently.

Does the 71V321L55JI8 support battery backup operation?

Yes, the 71V321L55JI8 supports battery backup operation with data retention down to 2.0 V V_CC. In data retention mode (CE high, all inputs at valid CMOS levels), it draws ≤500 µA typical current at 2 V, preserving memory contents during main power loss - a key feature for industrial and medical systems requiring state persistence.

How does the BUSY arbitration logic work in the 71V321L55JI8?

The 71V321L55JI8 asserts BUSYL or BUSYR when both ports attempt to access the same memory address simultaneously - determined solely by address and chip-enable matching, regardless of R/W state. The contested port's write is internally gated, and the BUSY output remains active until the winning port completes its access, enabling hardware-stall synchronization without software intervention.

What are the interrupt mailbox addresses for the 71V321L55JI8?

The 71V321L55JI8 uses two fixed interrupt mailbox addresses: writing to address 0x7FE (hex) on the right port sets the left-port INTL flag; writing to address 0x7FF (hex) on the left port sets the right-port INTR flag. Clearing is performed by reading those same addresses with OE and CE asserted - enabling simple, atomic interprocessor signaling.

Is the 71V321L55JI8 pin-compatible with other speed grades in the same family?

Yes, the 71V321L55JI8 shares identical pinout and package (52-pin PLCC) with other 71V321L variants including 71V321L25JI8 and 71V321L35JI8. All L-grade industrial-temperature PLCC versions use the PLG52 footprint and electrical interface, allowing speed-grade upgrades or downgrades without PCB modification - provided timing margins accommodate the selected grade.