Renesas 71V321S55PFI

Overview

71V321S55PFI from Renesas Electronics is a high-speed 3.3V 2K × 8 dual-port static RAM with on-chip interrupt logic and BUSY arbitration for interprocessor communication. It supports fully asynchronous access from left and right ports, delivers 55 ns read/write cycle time, consumes ≤55 mA dynamic current (typ.), and operates across –40°C to +85°C industrial temperature range in a 64-pin TQFP package. It is used in real-time embedded systems requiring concurrent memory access between two processors or DMA engines.

For engineers reviewing the 71V321S55PFI datasheet, 71V321S55PFI pinout, 71V321S55PFI application, or 71V321S55PFI equivalent, key selection criteria include dual-port arbitration timing (tBDD ≤ 45 ns), interrupt flag behavior (INTL/INTR set/clear via dedicated mailbox addresses 7FEh/7FFh), 2.0V data retention capability (L-version only), and compatibility with TTL-level 3.3V I/O signaling without level shifters.

Technical Context

The 71V321S55PFI implements independent left/right port control logic with separate CE, R/W, OE, address, and I/O buses - enabling true concurrent read/write operations. Its on-chip arbitration uses address and chip-enable matching (not data or R/W state) to assert BUSYL/BUSYR outputs, which are totem-pole (no pull-ups required) and gate writes internally when active.

Interrupt functionality relies on dedicated mailbox addresses: writing to 7FFh (right port) sets INTR; reading 7FFh clears it. Similarly, 7FEh controls INTL. These flags operate independently of BUSY status and support software-coordinated message passing between co-located processors without shared bus contention.

Key Specifications

Pinout & Package

71V321S55PFI is packaged in a 64-pin TQFP (PNG64), measuring 10 mm × 10 mm × 1.4 mm, with lead-free (Green) finish and RoHS compliance. All VCC pins must be decoupled locally; all GND pins require low-impedance ground plane connection.

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 71V321S55PFI uniquely integrates both BUSY arbitration and interrupt mailbox logic in a compact 2K × 8 footprint - reducing BOM count and eliminating timing-critical software coordination in tightly coupled dual-processor designs.

Availability

71V321S55PFI is available at Aetrix Electronics and suitable for real-time dual-core control, industrial PLC memory buffering, avionics data concentration, and medical imaging frame storage requiring stable component supply across extended production lifecycles.

Supply support for 71V321S55PFI 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 memory solutions for automotive, industrial, and infrastructure markets.

The 71V321S55PFI belongs to Renesas' legacy IDT dual-port SRAM product line, designed specifically for deterministic interprocessor communication in resource-constrained embedded systems where hardware arbitration and low-latency messaging are critical.

FAQ

What is the maximum operating frequency supported by the 71V321S55PFI?

The 71V321S55PFI does not operate from a clock signal - it is a fully asynchronous dual-port SRAM. Its timing is defined by access and cycle times: tAA ≤ 55 ns and tRC ≤ 55 ns. This corresponds to a maximum effective throughput of approximately 18.2 MHz per port under ideal conditions, assuming no wait states or arbitration delays. The 71V321S55PFI achieves this performance using CMOS high-speed process technology without requiring external clocks or synchronization circuitry.

Does the 71V321S55PFI support battery backup for data retention?

No - the 71V321S55PFI is the standard-power (S) version and does not support battery backup data retention. Only the low-power (L) variants (e.g., 71V321L55PFI) guarantee 2.0 V data retention with typical current draw of 100 µA. The 71V321S55PFI has higher active and standby currents (ISB3 ≤ 1.0 mA typ.) and lacks the internal circuitry for low-voltage retention mode. For battery-backed operation, select an L-suffix part number.

How do the BUSY signals function during simultaneous access to the same memory location?

When both ports attempt access to the same address, the 71V321S55PFI asserts BUSYL or BUSYR (but never both simultaneously) based on which port's address and CE signals stabilize first - determined by tAPS (arbitration priority setup time ≥ 5 ns). The winning port proceeds; the losing port's BUSY output goes low, and any write operation on that side is internally gated and ignored. Reads still return valid data after tBDD (BUSY disable to valid data ≤ 45 ns), ensuring deterministic resolution without bus lockup.

Can the interrupt flags (INTL/INTR) be used independently of the BUSY logic?

Yes - the interrupt flags (INTL and INTR) operate entirely independently of BUSY logic. INTL is asserted when the right port writes to address 7FEh; INTR is asserted when the left port writes to 7FFh. These actions do not require BUSY assertion, address collision, or any port arbitration event. Clearing is performed by reading the same address with appropriate CE/OE/RW settings. This allows software-defined message passing even when both ports operate on disjoint memory regions.

What package and lead finish does the 71V321S55PFI use?

The 71V321S55PFI uses a 64-pin TQFP package (package code PNG64), measuring 10 mm × 10 mm × 1.4 mm. It features a lead-free (RoHS-compliant) Green finish, consistent with Renesas' environmental compliance program. The device is supplied in tape-and-reel format (suffix 'G' or 'GI') and is rated for industrial temperature operation (–40°C to +85°C).