Renesas 71321LA20JG

Overview

IDT71321LA20JG from Integrated Device Technology (IDT) is a high-speed 2K × 8 dual-port static RAM with integrated interrupt and BUSY arbitration logic, designed as a MASTER device for interprocessor communication in real-time embedded systems. It delivers 20 ns max read cycle time, supports independent asynchronous access on left/right ports, features battery-backed data retention at 2 V, and operates across –40°C to +85°C industrial temperature range.

For engineers reviewing the IDT71321LA20JG datasheet, IDT71321LA20JG pinout, IDT71321LA20JG application, or IDT71321LA20JG equivalent, key selection considerations include its MASTER-only BUSY output capability, dual-interrupt mailbox addressing (7FEh/7FFh), low 1 µA full-standby current, and compatibility with 52-pin STQFP (PPG52) packaging for space-constrained industrial control modules.

Technical Context

The IDT71321LA20JG implements fully asynchronous dual-port architecture with separate address/control/I/O buses per port, enabling concurrent read/write operations without external synchronization. Its on-chip arbitration logic resolves port contention via BUSY flag generation based solely on chip enable (CEL/CER) and address match timing - not R/W state - ensuring deterministic write inhibition during simultaneous access to identical memory locations.

As a MASTER-only device, it provides open-drain BUSYL/BUSYR outputs requiring 270 Ω pull-up resistors, while supporting interrupt-driven messaging via dedicated mailbox addresses (7FEh for INTL, 7FFh for INTR). The LA variant enables battery backup operation with guaranteed 2 V data retention and ultra-low 100–4000 µA retention current depending on grade.

Key Specifications

Pinout & Package

Package: 52-pin STQFP (PPG52), 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-20AXC and 23LCV1024-I/P, the IDT71321LA20JG uniquely integrates MASTER arbitration, dual-interrupt mailboxes, and 2 V data retention - making it irreplaceable in deterministic real-time interprocessor communication where hardware-enforced synchronization and fail-safe state preservation are mandatory.

Availability

IDT71321LA20JG is available at Aetrix Electronics and suitable for industrial PLC communication hubs, real-time motor control co-processors, medical imaging data pipelines, and avionics sensor fusion modules requiring stable component supply with long-term lifecycle assurance.

Supply support for IDT71321LA20JG 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.

IDT71321LA20JG belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in hard real-time systems where hardware arbitration, low-latency interrupts, and battery-backed data retention are essential design requirements.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321LA20JG?

BUSYL and BUSYR are open-drain output flags on the IDT71321LA20JG indicating port contention - they go LOW when both ports attempt simultaneous access to the same memory location. As a MASTER device, IDT71321LA20JG asserts these outputs to block writes on the contending port; external 270 Ω pull-up resistors are required per datasheet Figure 3. These signals are not inputs and cannot be driven by external sources on IDT71321LA20JG.

Does the IDT71321LA20JG support SLAVE mode operation?

No, the IDT71321LA20JG is exclusively a MASTER device. It contains on-chip arbitration logic and BUSY output circuitry but lacks the BUSY input functionality required for SLAVE operation. For SLAVE pairing, IDT71421LA20JG must be used - it accepts BUSY as an input to inhibit writes. The IDT71321LA20JG cannot function as a SLAVE in any configuration per Truth Table III and Functional Description on page 15–16 of the datasheet.

How do the interrupt mailboxes (7FEh and 7FFh) work on the IDT71321LA20JG?

On the IDT71321LA20JG, writing to address 7FEh (hex) with CER = R/WR = VIL sets the INTL flag, signaling the left port; writing to 7FFh sets the INTR flag, signaling the right port. Clearing is performed by reading those addresses with corresponding CE/OE asserted. These are dedicated hardware mailboxes - no configuration registers are involved. The data written becomes the 8-bit message payload, accessible immediately upon interrupt assertion.

What is the minimum supply voltage for data retention on the IDT71321LA20JG?

The IDT71321LA20JG guarantees data retention down to 2.0 V DC on VCC, as specified in Table 6 (Data Retention Characteristics). At this voltage, typical retention current is 100 µA (commercial) or up to 4000 µA (industrial grade), with no access allowed. This feature enables reliable state preservation during main power interruption using a backup battery or supercapacitor, and is exclusive to LA variants - SA versions do not support 2 V retention.

Which package does the IDT71321LA20JG use, and are there pin-compatible alternatives?

IDT71321LA20JG uses the 52-pin STQFP (PPG52) package, measuring 10 mm × 10 mm × 1.4 mm. While IDT offered the same speed grade in 52-pin PLCC (PLG52) and 64-pin TQFP (PNG64), those are not pin-compatible due to differing pin counts and assignments. No drop-in pin-compatible alternative exists across manufacturers - Cypress, Microchip, and ON Semiconductor dual-port SRAMs use different pinouts, voltage domains, or arbitration architectures, requiring PCB redesign for substitution.