Renesas 71321LA35J

Overview

71321LA35J from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM with interrupt logic and BUSY arbitration, designed as a MASTER device for interprocessor communication. It delivers 35 ns max read cycle time, 2V data retention in battery backup mode, industrial temperature operation (–40°C to +85°C), and supports fully asynchronous dual-port access with independent left/right control. It is used in real-time embedded systems requiring deterministic port-to-port handshaking, such as motor control co-processors.

For engineers reviewing the 71321LA35J datasheet, 71321LA35J pinout, 71321LA35J application, or 71321LA35J equivalent, this page provides verified technical context, validated pin functions, confirmed low-power standby behavior (1 µA full standby), and precise interrupt timing (tINS ≤ 25 ns) - all specific to the LA-grade 35 ns speed bin in PLCC/STQFP/TQFP packages.

Technical Context

The 71321LA35J implements on-chip arbitration logic that resolves simultaneous accesses to identical addresses using chip enable and address match detection - not R/W state - and asserts open-drain BUSY outputs (requiring 270 Ω pull-up) to inhibit writes on contention. Its interrupt system uses dedicated mailbox addresses (7FE_H for INTL, 7FF_H for INTR) with hardware-set/clear semantics tied to write cycles on the opposite port.

It operates exclusively at 5.0 V ±10% with TTL-compatible I/O, supports two independent asynchronous ports (left/right), and features automatic power-down via CE control per port. The LA variant guarantees 2 V data retention with ICCDR ≤ 1500 µA (commercial) or ≤ 4000 µA (industrial), enabling nonvolatile memory hold during main supply loss.

Key Specifications

Pinout & Package

71321LA35J is available in 52-pin PLCC (PLG52), 52-pin STQFP (PPG52), and 64-pin TQFP/STQFP (PNG64/PPG64) packages. Pin functions are identical across packages; only mechanical dimensions and thermal characteristics differ.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1371D-133AXC and IS61WV20488BLL-10MLI, the 71321LA35J uniquely integrates arbitration, interrupt, and 2V retention in a single 5 V-compatible package - eliminating design complexity for deterministic, low-latency, fail-safe dual-processor interfaces.

Availability

71321LA35J is available at Aetrix Electronics and suitable for industrial motor control, avionics sensor fusion, and railway signaling applications requiring stable component supply, long-term lifecycle support, and guaranteed 2V data retention capability.

Supply support for 71321LA35J 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 signal conditioning ICs for communications, computing, and industrial markets.

The IDT71321 family was designed specifically for deterministic interprocessor communication in real-time embedded systems - delivering hardware-enforced arbitration, low-latency interrupts, and battery-backed data retention without external components.

FAQ

What is the guaranteed data retention voltage for 71321LA35J?

The 71321LA35J guarantees data retention down to 2.0 V (V_DR) with ICCDR ≤ 1500 µA (commercial grade) or ≤ 4000 µA (industrial grade). This enables direct connection to backup power sources like lithium coin cells or supercapacitors without additional regulation or monitoring circuitry - a key differentiator from SA-grade variants.

How does BUSY arbitration work on 71321LA35J, and what external components are required?

71321LA35J implements hardware BUSY arbitration based solely on chip enable (CE) and address match timing - not R/W state. When both ports access the same address, it asserts open-drain BUSYL/BUSYR outputs, which require external 270 Ω pull-up resistors to V_CC. These signals directly inhibit writes on the contending port, eliminating need for external logic gates or software intervention.

Can 71321LA35J be used as a SLAVE device in a master/slave configuration?

No - 71321LA35J is strictly a MASTER device. It features on-chip arbitration logic, BUSY outputs, and interrupt generation capability. The SLAVE counterpart is the IDT71421LA35J, which has BUSY inputs (not outputs) and no arbitration logic. Using 71321LA35J as a slave would violate functional specifications and cause undefined behavior.

What are the exact interrupt mailbox addresses for 71321LA35J, and how are they cleared?

The left-port interrupt (INTL) is asserted when the right port writes to address 7FE_H; it is cleared when the left port performs a read or write to 7FE_H with CEL = OEL = VIL. The right-port interrupt (INTR) is asserted on left-port write to 7FF_H and cleared by right-port access to 7FF_H under the same conditions. These are fixed hardware-mapped locations, not configurable registers.

Which packages are available for 71321LA35J, and are pinouts identical across them?

71321LA35J is offered in 52-pin PLCC (PLG52), 52-pin STQFP (PPG52), and 64-pin TQFP/STQFP (PNG64/PPG64). Pin functions are electrically and logically identical across all packages; only mechanical footprint, thermal resistance, and pin pitch differ. The 64-pin versions include additional NC and GND pins for improved noise immunity and power integrity.