Renesas 71321LA55PPGI

Overview

IDT71321LA55PPGI 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 55 ns max access time, industrial temperature range (–40°C to +85°C), 2 V data retention capability, TTL-compatible 5 V ±10% supply, and 64-pin STQFP package. It enables error-free 16-bit-or-wider memory expansion when paired with IDT71421 SLAVE devices.

For engineers reviewing the IDT71321LA55PPGI datasheet, IDT71321LA55PPGI pinout, IDT71321LA55PPGI application, or IDT71321LA55PPGI equivalent, key selection considerations include its MASTER-only BUSY output behavior, interrupt mailbox addressing (7FEh/7FFh), dual-port asynchronous timing constraints (tBDD, tWDD), and battery backup support - all critical for deterministic multi-processor shared-memory designs.

Technical Context

The IDT71321LA55PPGI implements on-chip port arbitration logic that asserts BUSYL/BUSYR outputs based solely on chip enable (CEL/CER) and address match timing - independent of R/W state - to prevent simultaneous writes to the same location. Its interrupt logic uses dedicated mailbox addresses (7FEh for INTL, 7FFh for INTR) with set/reset via write/read cycles, enabling hardware-synchronized message passing between ports.

As a MASTER-only device, it drives open-drain BUSY outputs requiring 270 Ω pull-up resistors, while supporting full asynchronous operation from either port. The LA variant delivers 1 µA typical standby current at 5 V and retains data down to 2 V, making it suitable for battery-backed systems where power loss resilience is required.

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-55AXC and R1EX24024AS0I#U0, the IDT71321LA55PPGI uniquely integrates MASTER-mode BUSY arbitration and interrupt mailboxes in a 5 V, 2 V-retentive package - reducing BOM count and eliminating timing-critical software arbitration loops.

Availability

IDT71321LA55PPGI is available at Aetrix Electronics and suitable for industrial PLCs, avionics data bridges, battery-backed telemetry nodes, and real-time dual-processor communication systems requiring stable component supply across extended product lifecycles.

Supply support for IDT71321LA55PPGI 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 high-performance silicon solutions for communications, computing, and industrial markets.

IDT71321LA55PPGI belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in real-time embedded systems where hardware arbitration and low-power data retention are essential.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321LA55PPGI?

BUSYL and BUSYR are open-drain output flags on the IDT71321LA55PPGI indicating port contention - asserted LOW when both ports attempt simultaneous access to the same memory location. They require 270 Ω pull-up resistors and serve as hardware write-inhibit signals in MASTER/SLAVE configurations. Unlike SLAVE devices, IDT71321LA55PPGI never accepts BUSY as an input.

How does the interrupt functionality work in the IDT71321LA55PPGI?

The IDT71321LA55PPGI uses fixed SRAM addresses 7FEh (for INTL) and 7FFh (for INTR) as interrupt mailboxes. Writing to 7FEh from the right port sets INTL; reading 7FEh from the left port clears it. Similarly, writing to 7FFh from the left port sets INTR, and reading 7FFh from the right port clears it. These are hardware-asserted, open-drain outputs requiring pull-ups.

Can the IDT71321LA55PPGI operate with a 3.3 V supply?

No. The IDT71321LA55PPGI is specified only for 5.0 V ±10% operation (4.5 V to 5.5 V). Its inputs are TTL-compatible, and DC/AC characteristics assume 5 V supply. Using 3.3 V will result in undefined behavior, failed timing margins, and potential data corruption - it is not 3.3 V tolerant.

What is the significance of the 'LA' suffix in IDT71321LA55PPGI?

The 'LA' suffix denotes the low-power, battery-backup variant of the IDT71321. It guarantees 2 V data retention and achieves 0.2 mA typical full-standby current (ISB3) at 5 V - significantly lower than the SA version. This makes IDT71321LA55PPGI suitable for systems requiring memory hold during brown-out or battery fallback conditions.

Is the IDT71321LA55PPGI pin-compatible with the IDT71421LA55PPGI?

No. The IDT71321LA55PPGI is a MASTER device with BUSYL/BUSYR as outputs and integrated arbitration logic, while the IDT71421LA55PPGI is a SLAVE device with BUSYL/BUSYR as inputs and no arbitration. Their pin functions differ critically at BUSY and interrupt pins - direct substitution would cause functional failure. They are complementary, not interchangeable.