Renesas 71321SA25TF8

Overview

71321SA25TF8 from Integrated Device Technology (IDT) is a high-speed 2K × 8 dual-port static RAM configured as a MASTER device with on-chip port arbitration, two interrupt flags (INTL/INTR), and BUSY output logic. It operates at 25 ns max access time, supports TTL-compatible 5V ±10% supply, and delivers 325 mW typical active power in industrial temperature range (–40°C to +85°C). It is used in real-time interprocessor communication systems requiring concurrent read/write access without external arbitration logic.

For engineers reviewing the 71321SA25TF8 datasheet, 71321SA25TF8 pinout, 71321SA25TF8 application, or 71321SA25TF8 equivalent, key selection considerations include its MASTER-only arbitration capability, open-drain BUSY output requiring 270 Ω pull-up, interrupt mailbox addressing (7FEh/7FFh), and compatibility with IDT71421SLAVE devices for 16-bit+ bus expansion.

Technical Context

The 71321SA25TF8 implements fully asynchronous dual-port operation with independent left/right address, control, and I/O buses. Its on-chip arbitration logic resolves contention by asserting BUSYL/BUSYR outputs based on chip enable (CEL/CER) and address match timing - not R/W state - ensuring deterministic priority when both ports access the same location.

Interrupt generation is memory-mapped: writing to address 7FEh (right port) sets INTL; writing to 7FFh (left port) sets INTR. Clearing requires read-access to the same address with OE enabled. The device supports battery backup data retention only in LA variants; this SA variant does not support 2V retention mode.

Key Specifications

Pinout & Package

71321SA25TF8 is packaged in a 64-pin STQFP (PPG64), measuring 10 mm × 10 mm × 1.4 mm, with exposed pad for thermal dissipation. Pin functions are electrically and physically identical to the 64-pin TQFP (PNG64) variant per IDT documentation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-25AXC, 71321SA25TF8 provides integrated arbitration and interrupt logic but requires 5V supply and offers narrower 8-bit bus. Compared with IDT71421SA25TF8, it enables standalone dual-port operation and eliminates dependency on external MASTER coordination.

Availability

71321SA25TF8 is available at Aetrix Electronics and suitable for real-time interprocessor communication, redundant control systems, and bus width expansion applications requiring stable component supply, long-term industrial-grade availability, and consistent parametric performance across production lots.

Supply support for 71321SA25TF8 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 solutions for communications, computing, and industrial markets.

The IDT71321/71421 family was designed specifically for deterministic, low-latency interprocessor communication in embedded control systems - emphasizing hardware arbitration, interrupt signaling, and seamless MASTER/SLAVE scalability without external logic.

FAQ

What is the function of the BUSY pins on the 71321SA25TF8?

The BUSYL and BUSYR pins on the 71321SA25TF8 are open-drain outputs that signal write contention when both ports attempt to access the same memory location. They require a 270 Ω pull-up resistor to VCC. When asserted (low), they inhibit writes on the respective port. This hardware arbitration eliminates race conditions and replaces external logic in MASTER/SLAVE configurations. The 71321SA25TF8 implements this as a MASTER device only.

How do the interrupt flags (INTL and INTR) operate in the 71321SA25TF8?

In the 71321SA25TF8, INTL is asserted when the right port writes to address 7FEh; INTR is asserted when the left port writes to 7FFh. Both flags are active-low, open-drain outputs requiring pull-up. To clear INTL, the left port must read from 7FEh with CEL and OEL low; to clear INTR, the right port reads from 7FFh with CER and OER low. These are standard SRAM locations - no special register mapping is involved. The 71321SA25TF8 uses this mailbox mechanism for lock-free interprocessor signaling.

Is the 71321SA25TF8 compatible with battery backup operation?

No, the 71321SA25TF8 is an SA (Standard Active) variant and does not support battery backup data retention. Only LA (Low-power Active) variants like 71321LA25TF8 guarantee 2V data retention with typical current draw of 100 µA. The 71321SA25TF8 specifies standby current down to 30 mA (ISB1) under TTL-level inputs but lacks the internal circuitry for sub-2V retention mode. For battery-backed applications, the LA version must be selected.

Can the 71321SA25TF8 be used as a standalone dual-port RAM without a SLAVE device?

Yes, the 71321SA25TF8 is fully functional as a standalone dual-port SRAM. Its on-chip arbitration logic, BUSY outputs, and interrupt flags operate independently - no SLAVE device is required. It is commonly deployed in point-to-point interprocessor links or as a shared buffer between CPU and FPGA/DSP. The SLAVE (IDT71421) is optional and used only when expanding data bus width beyond 8 bits using MASTER/SLAVE topology. The 71321SA25TF8 does not depend on external coordination for basic dual-port operation.

What package type does the 71321SA25TF8 use, and are pinouts compatible with other variants?

71321SA25TF8 uses a 64-pin STQFP (PPG64) package, 10 mm × 10 mm × 1.4 mm, with exposed thermal pad. Its pinout is identical to the 64-pin TQFP (PNG64) variant and electrically compatible with the 52-pin PLCC and STQFP versions - though pin count differs, the signal mapping for shared pins (A0–A10, I/O0–I/O7, CE, OE, R/W, INT, BUSY) remains consistent across all packages. This enables footprint flexibility and design reuse across form factors without logic changes.