Renesas 71321LA35PF

Overview

IDT71321LA35PF from Integrated Device Technology 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 delivers 35 ns max read cycle time, 2V battery-backed data retention, industrial temperature operation (–40°C to +85°C), and supports fully asynchronous dual-port access - used in redundant control modules requiring deterministic port-to-port handshaking.

For engineers reviewing the IDT71321LA35PF datasheet, IDT71321LA35PF pinout, IDT71321LA35PF application, or IDT71321LA35PF equivalent, key selection criteria include its MASTER-only arbitration logic, open-drain BUSY output requiring 270 Ω pull-up, 52-pin STQFP package, and LA-series ultra-low standby current (1 mW typ.) enabling battery backup operation.

Technical Context

The IDT71321LA35PF implements on-chip port arbitration logic that resolves contention between left and right ports using address and chip-enable timing - asserting BUSYL/BUSYR outputs when both ports access identical addresses simultaneously. Its interrupt system uses dedicated mailbox addresses (7FE_H for INTL, 7FF_H for INTR) to signal cross-port events without software polling.

As a MASTER-only device, it features open-drain BUSY outputs (requiring external 270 Ω pull-up resistors), supports CE-controlled and R/W-controlled write cycles, and enables width expansion with SLAVE IDT71421 devices without external logic. It operates at 5.0 V ±10% with TTL-compatible I/O and full CMOS-level standby control.

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 IDT71321SA35PF and CY7C024AV-35AXC, the IDT71321LA35PF uniquely combines 2V data retention, MASTER arbitration, and hardware interrupt mailboxes in a single 52-pin STQFP package - eliminating discrete logic and reducing firmware overhead in battery-backed real-time systems.

Availability

IDT71321LA35PF is available at Aetrix Electronics and suitable for redundant control systems, real-time interprocessor communication, industrial PLC backplane memory, and battery-backed data loggers requiring stable component supply across extended production lifecycles.

Supply support for IDT71321LA35PF 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 power solutions for communications and industrial markets.

The IDT71321LA35PF belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic, low-latency interprocessor communication in safety-critical and battery-constrained embedded systems.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321LA35PF?

BUSYL and BUSYR are open-drain output flags indicating port contention when both left and right ports attempt to access the same memory address simultaneously. On the IDT71321LA35PF - configured as MASTER - these signals must be pulled up with 270 Ω resistors to V_CC. When asserted (LOW), they inhibit writes on the contending port, ensuring data integrity without software intervention.

Does the IDT71321LA35PF support battery backup operation?

Yes, the IDT71321LA35PF supports true battery backup operation with guaranteed data retention down to 2.0 V V_CC. In retention mode, it draws only 100–1500 µA (ICCDR), enabling multi-year operation on small coin cells. This feature is exclusive to LA-grade parts and is not available on SA variants like IDT71321SA35PF.

How do the interrupt mailboxes (7FE_H and 7FF_H) work on the IDT71321LA35PF?

The IDT71321LA35PF uses address 7FE_H to set the left-port interrupt flag (INTL) and 7FF_H to set the right-port flag (INTR). Writing to either location with the opposite port asserts the corresponding open-drain flag within 25 ns (t_INS). Clearing is performed by reading the same address - enabling hardware-synchronized, zero-latency interprocessor messaging without polling.

Can the IDT71321LA35PF be used as a SLAVE device in a width-expanded array?

No, the IDT71321LA35PF is exclusively a MASTER device. Its BUSYL and BUSYR pins are open-drain outputs, and it contains on-chip arbitration logic - characteristics incompatible with SLAVE operation. For width expansion, pair IDT71321LA35PF with IDT71421LA35PF (SLAVE), which accepts BUSY as an input to inhibit writes during contention.

What is the significance of the 'LA' suffix in IDT71321LA35PF?

The 'LA' suffix denotes the Low-Power Active/Standby variant: it delivers 1 mW typical standby power (vs. 5 mW for 'SA'), enables 2V data retention, and targets battery-backed or energy-sensitive applications. The '35' indicates 35 ns maximum access time, and 'PF' specifies the 52-pin STQFP (PPG52) package - confirming the full identity as IDT71321LA35PF.