Renesas 71321LA25PFGI

Overview

IDT71321LA25PFGI from Integrated Device Technology (IDT) is a high-speed 2K × 8 dual-port static RAM with interrupt and BUSY arbitration logic, designed as a MASTER device for interprocessor communication in real-time embedded systems. It features 25 ns max access time, industrial temperature range (–40°C to +85°C), 1 mW standby power, 2 V data retention capability, and operates on a single 5 V ±10% supply - deployed in motor control co-processor interfaces requiring deterministic memory access.

For engineers reviewing the IDT71321LA25PFGI datasheet, IDT71321LA25PFGI pinout, IDT71321LA25PFGI application, or IDT71321LA25PFGI equivalent, key selection criteria include dual-port arbitration timing (tBAA ≤ 20 ns), interrupt mailbox address mapping (7FEH/7FFH), BUSY open-drain output drive requirement (270 Ω pull-up), and compatibility with IDT71421LA slave expansion for 16-bit+ bus width.

Technical Context

The IDT71321LA25PFGI implements fully asynchronous dual-port operation with independent left/right address, control, and I/O buses - enabling concurrent read/write access without internal synchronization overhead. Its on-chip arbitration logic resolves port contention via BUSY flag assertion based solely on chip enable (CEL/CER) and address match timing, independent of R/W direction.

As a MASTER-only device, it provides two open-drain BUSY outputs (BUSYL/BUSYR) and two interrupt flags (INTL/INTR), with interrupt set/reset triggered by writes to dedicated SRAM addresses (7FEH and 7FFH). The LA variant supports battery backup with guaranteed 2 V data retention and ultra-low full-standby current (0.2 mA typ).

Key Specifications

Pinout & Package

Package: 64-pin STQFP (PPG64), 10 mm × 10 mm × 1.4 mm body, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-25AXC and R1EX24002AS0C-25#U0, IDT71321LA25PFGI uniquely integrates hardware arbitration and interrupt mailboxes in a 2K × 8 footprint - reducing BOM count, PCB area, and firmware development effort for tightly coupled dual-CPU systems.

Availability

IDT71321LA25PFGI is available at Aetrix Electronics and suitable for motor control co-processors, redundant safety PLCs, avionics display buffers, and industrial Ethernet gateways requiring stable component supply across extended product lifecycles.

Supply support for IDT71321LA25PFGI 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, and RF solutions for communications, computing, and industrial markets.

IDT71321LA25PFGI belongs to IDT's high-speed dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in real-time embedded systems - emphasizing hardware-enforced arbitration, low-latency interrupts, and industrial reliability.

FAQ

What is the function of the BUSY pins on the IDT71321LA25PFGI?

The BUSYL and BUSYR pins on the IDT71321LA25PFGI are open-drain outputs that assert LOW when port contention is detected - indicating that a write to the same memory location is in progress on the opposite port. This hardware signal directly inhibits writes on the contending port, ensuring data coherency without software intervention. Each BUSY pin requires a 270 Ω pull-up resistor per datasheet Figure 3. The IDT71321LA25PFGI uses these signals exclusively as outputs (MASTER role), unlike the SLAVE IDT71421 which accepts BUSY as an input.

How do the interrupt mailboxes work in the IDT71321LA25PFGI?

The IDT71321LA25PFGI implements interrupt signaling via two fixed SRAM addresses: writing to 7FEH sets the left-port INTL flag, and writing to 7FFH sets the right-port INTR flag. These flags are cleared automatically when the corresponding address is read with CE and OE asserted. Because these locations reside within the normal memory map, they retain user-defined 8-bit data - enabling mailbox-style messaging between processors. No configuration registers or initialization sequence is required; the functionality is hardwired and active upon power-up.

Does the IDT71321LA25PFGI support battery backup operation?

Yes, the IDT71321LA25PFGI (LA suffix) supports battery backup operation with guaranteed data retention down to 2.0 V VCC, as specified in Table 6 of the datasheet. In retention mode, ICCDR is limited to 100 µA (typ) at 2.0 V and 25°C. This feature is exclusive to LA variants - SA versions lack retention capability. The device enters retention automatically when VCC drops below the operating range, provided CE remains asserted and no active accesses occur.

Can the IDT71321LA25PFGI be used without the BUSY arbitration logic?

Yes, the IDT71321LA25PFGI can operate without BUSY arbitration by holding both BUSYL and BUSYR inputs HIGH (via pull-ups) and ignoring their states - effectively disabling hardware contention resolution. In this mode, the device functions as a standard dual-port SRAM with independent left/right access. However, software must manage memory coherency, and simultaneous writes to the same address may result in undefined data. The arbitration logic is not disableable via register; its use is optional but recommended for deterministic real-time systems.

What package and pin count does the IDT71321LA25PFGI use?

The IDT71321LA25PFGI is packaged in a 64-pin STQFP (PPG64) with 10 mm × 10 mm × 1.4 mm dimensions, as confirmed in Pin Configuration diagrams on pages 3 and 4 of the datasheet. It is not offered in PLCC or 52-pin variants - those apply to other speed grades or SA versions. All VCC and GND pins must be connected per Note 1 and 2; unused NC pins (e.g., pins 12, 13, 24, 25, 37, 38, 49–52) must remain unconnected and floating.