Renesas 71V321L25PFG

Overview

71V321L25PFG from Renesas Electronics (formerly IDT) is a high-speed 3.3V 2K × 8 dual-port static RAM with independent left/right ports, on-chip interrupt logic, and BUSY arbitration. It delivers 25 ns max access time, supports battery backup data retention down to 2V, and operates across commercial temperature range (0°C to +70°C) in a 64-pin TQFP package. It is used in real-time interprocessor communication systems requiring concurrent memory access without software coordination.

For engineers reviewing the 71V321L25PFG datasheet, 71V321L25PFG pinout, 71V321L25PFG application, or 71V321L25PFG equivalent, key selection criteria include dual-port asynchronous timing, interrupt mailbox addressing (7FEh/7FFh), BUSY-driven contention resolution, low-power standby (≤0.2 mA), and TTL-compatible 3.3V operation with no external pull-ups required for BUSY/INT outputs.

Technical Context

The 71V321L25PFG implements fully asynchronous dual-port architecture with separate address, control, and I/O buses per port-enabling simultaneous read/write operations to distinct memory locations. Its internal arbitration logic uses address and chip-enable signals (not R/W state) to detect port-to-port contention and assert BUSYL/BUSYR as totem-pole outputs.

Interrupt functionality relies on dedicated mailbox addresses: writing to 7FFh via the left port sets INTR (right port flag), while writing to 7FEh via the right port sets INTL (left port flag); clearing is performed by reading those same addresses with OE and CE asserted. Data retention at 2V is guaranteed only for the "L" (low-power) variant.

Key Specifications

Pinout & Package

71V321L25PFG is housed in a 64-pin Thin Quad Flatpack (TQFP) with exposed pad, compliant with JEDEC MO-159. Pin functions are symmetrically distributed for left (L) and right (R) ports, including dual BUSY and INT flags, independent CE/OE/R/W controls, and 11-bit address + 8-bit bidirectional I/O per port.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C136-25JC and AS7C3256B-25JIN, the 71V321L25PFG uniquely integrates hardware arbitration and interrupt signaling in a compact 64-pin TQFP-reducing BOM count by ≥3 discrete logic ICs and eliminating software arbitration latency in safety-critical embedded systems.

Availability

71V321L25PFG is available at Aetrix Electronics and suitable for industrial PLC communication hubs, telecom line card buffers, avionics sensor fusion modules, and medical imaging data pipelines requiring stable component supply and long-term lifecycle support.

Supply support for 71V321L25PFG 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, infrastructure, and IoT applications.

The 71V321L25PFG belongs to Renesas' legacy dual-port SRAM product line-designed specifically for deterministic interprocessor communication in real-time embedded systems where software arbitration introduces unacceptable latency or complexity.

FAQ

What is the maximum operating frequency supported by the 71V321L25PFG?

The 71V321L25PFG does not operate on a clock signal-it is fully asynchronous. Its performance is defined by timing parameters: maximum read cycle time (tRC) is 25 ns, meaning it supports effective throughput up to 40 MHz in burst-read scenarios. Actual system speed depends on host interface timing margins, not an internal oscillator.

Does the 71V321L25PFG require external pull-up resistors on BUSY or INT pins?

No. The 71V321L25PFG features totem-pole BUSYL and BUSYR outputs, and INTL/INTR outputs designed for open-drain compatibility but internally driven-no external pull-ups are required. This simplifies PCB layout and reduces component count compared to open-drain alternatives.

How does the 71V321L25PFG handle simultaneous access to the same memory address from both ports?

When both ports attempt access to the same address, the 71V321L25PFG asserts BUSYL or BUSYR (but never both) based on input timing alignment. The port receiving BUSY = LOW has its write operation internally gated-preventing data corruption. Read operations remain valid after tBDD delay (≤45 ns), ensuring deterministic resolution without software intervention.

Can the 71V321L25PFG retain data during main power failure?

Yes. As an "L" (low-power) variant, the 71V321L25PFG guarantees data retention down to 2.0 V supply voltage. When main VCC drops below operational threshold, applying ≥2.0 V via backup battery to VCC pins preserves all 2K × 8 bits for up to 1000 µs (tCDR), enabling graceful shutdown or state recovery.

What are the valid interrupt mailbox addresses for the 71V321L25PFG?

The 71V321L25PFG uses two fixed SRAM locations as hardware interrupt mailboxes: address 7FEh (hex) triggers INTL when written by the right port, and address 7FFh (hex) triggers INTR when written by the left port. Clearing is performed by reading those addresses with OE and CE asserted-no special control registers are involved.