Renesas 71321SA25TF

Overview

IDT71321SA25TF from Integrated Device Technology (IDT) is a high-speed 2K × 8 dual-port static RAM with on-chip interrupt logic and BUSY arbitration, designed as a MASTER device for interprocessor communication in real-time embedded systems. It delivers 25 ns max access time, operates at 5V ±10%, supports industrial temperature range (–40°C to +85°C), and features two independent asynchronous ports with TTL-compatible I/O - used in multiprocessing data exchange, shared memory buffers, and real-time control subsystems.

For engineers reviewing the 71321SA25TF datasheet, 71321SA25TF pinout, 71321SA25TF application, or 71321SA25TF equivalent, key selection criteria include its MASTER-only arbitration logic, open-drain BUSY output requiring 270Ω pull-up, interrupt mailbox addressing (7FEH/7FFH), and compatibility with IDT71421 SLAVE devices for 16-bit+ width expansion.

Technical Context

The 71321SA25TF implements fully asynchronous dual-port operation with separate address, control, and I/O buses per port - enabling concurrent read/write access without external synchronization. Its on-chip arbitration logic monitors CE and address signals (not R/W state) to assert BUSY outputs when port contention occurs on matching addresses.

As a MASTER-only device, it provides BUSYL and BUSYR as open-drain outputs (requiring external 270Ω pull-ups), while supporting interrupt generation via dedicated mailbox addresses (7FEH for INTL, 7FFH for INTR). The LA variant adds 2V battery backup retention; this SA variant does not support data retention below 4.5V.

Key Specifications

Pinout & Package

71321SA25TF is packaged in a 52-pin STQFP (PPG52), measuring 10 mm × 10 mm × 1.4 mm, with exposed thermal pad (not electrically connected). 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 CY7C136-25JC, the 71321SA25TF integrates hardware arbitration and interrupt signaling - reducing design complexity and improving determinism. Unlike IDT71421SA25TF, it provides MASTER functionality essential for autonomous contention resolution and mailbox-based IPC.

Availability

71321SA25TF is available at Aetrix Electronics and suitable for industrial PLC communication buffers, real-time motor control shared memory, and avionics data acquisition interfaces requiring stable component supply, long-term lifecycle support, and verified industrial-temperature performance.

Supply support for 71321SA25TF 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 sensor signal conditioning ICs for high-performance computing and industrial applications.

The IDT71321 family was engineered specifically for deterministic interprocessor communication in real-time embedded systems - delivering hardware-accelerated arbitration and interrupt signaling to eliminate software coordination overhead in dual-CPU architectures.

FAQ

What is the operating voltage range for the 71321SA25TF?

The 71321SA25TF operates over 4.5 V to 5.5 V (5.0 V ±10%), with all DC and AC specifications guaranteed across this range. It does not support battery backup or data retention below 4.5 V - that capability is exclusive to the LA variant (e.g., 71321LA25TF).

Does the 71321SA25TF support true simultaneous read/write operations on both ports?

Yes, the 71321SA25TF supports fully asynchronous, independent read and write operations on left and right ports - provided addresses do not match. When addresses match, on-chip arbitration asserts BUSYL or BUSYR to inhibit writes, ensuring data coherency without external logic.

How are the interrupt flags INTL and INTR controlled in the 71321SA25TF?

INTL is asserted when the right port writes to address 7FEH; INTR is asserted when the left port writes to 7FFH. Both flags are cleared by reading the same address with OE active - e.g., reading 7FEH with OEL = VIL clears INTL. These are hardware-generated, not software-pollable registers.

Can the 71321SA25TF be used without external pull-up resistors on BUSY and INT pins?

No - BUSYL, BUSYR, INTL, and INTR are open-drain outputs per datasheet Note 1 and Figure 3. Each requires a 270Ω pull-up resistor to VCC to ensure proper HIGH-level assertion and wired-OR compatibility in multi-Master configurations.

Is the 71321SA25TF pin-compatible with the IDT71421SA25TF?

No - although both share the same 52-pin STQFP (PPG52) package and pin count, their BUSY and interrupt pin functions differ fundamentally: 71321SA25TF has BUSYL/BUSYR as outputs and INTL/INTR as outputs, while IDT71421SA25TF has BUSYL/BUSYR as inputs and no interrupt generation capability. They are functionally complementary, not interchangeable.