Renesas 71421SA35PF8

Overview

71421SA35PF8 from Integrated Device Technology is a high-speed 2K × 8 dual-port static RAM configured as a SLAVE device in MASTER/SLAVE memory expansion systems, supporting fully asynchronous port-to-port access with 35 ns read cycle time, TTL-compatible 5 V ±10% supply, and industrial temperature range (–40°C to +85°C). It serves as a width-expansion companion to the IDT71321 MASTER in 16-bit-or-wider memory subsystems for real-time interprocessor communication.

For engineers reviewing the 71421SA35PF8 datasheet, 71421SA35PF8 pinout, 71421SA35PF8 application, or 71421SA35PF8 equivalent, key selection criteria include BUSY input behavior, interrupt flag compatibility with address 7FF/7FE, 35 ns timing compliance, 64-pin TQFP package footprint, and SLAVE-specific arbitration logic-critical for deterministic dual-processor shared-memory designs.

Technical Context

The 71421SA35PF8 implements a dedicated SLAVE architecture: BUSY is an input (not output), enabling write-inhibit control from a MASTER IDT71321; it lacks on-chip arbitration logic and relies entirely on external BUSY assertion for contention resolution. Its interrupt functionality is symmetric-INTL and INTR flags are set by cross-port writes to fixed addresses (7FE_H and 7FF_H) and cleared by local reads.

All timing parameters-including tWC = 35 ns, tBDD ≤ 50 ns, and tWDD ≤ 80 ns-are specified under commercial-only speed grade X35 and validated at V_CC = 5.0 V ±10%, TA = –40°C to +85°C. The device supports two independent asynchronous ports with separate CE/OE/R/W controls, I/O drivers, and address decoders-no shared internal bus or clock domain.

Key Specifications

Pinout & Package

71421SA35PF8 is packaged in a 64-pin TQFP (PNG64) with 0.5 mm pitch, 14 mm × 14 mm body, and exposed thermal pad. Pin assignments follow the standard IDT71421 layout per datasheet DSC-2691/17.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-35AXC and IDT71321SA35PF8, the 71421SA35PF8 uniquely delivers SLAVE-specific BUSY input behavior and interrupt mailbox addressing in a 5 V, industrial-temperature 2K × 8 configuration-making it irreplaceable in existing IDT MASTER/SLAVE designs requiring exact functional partitioning.

Availability

71421SA35PF8 is available at Aetrix Electronics and suitable for real-time interprocessor communication, redundant control system memory, and industrial PLC dual-core data exchange requiring stable component supply, long-term lifecycle support, and verified industrial temperature performance.

Supply support for 71421SA35PF8 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 computing solutions.

The IDT71421 product line was designed specifically for deterministic dual-processor shared-memory architectures, emphasizing hardware arbitration, interrupt signaling, and seamless width expansion-targeting aerospace, industrial automation, and telecom infrastructure.

FAQ

Is 71421SA35PF8 a standalone dual-port RAM or does it require a MASTER device?

71421SA35PF8 is a SLAVE-only device and requires pairing with an IDT71321 MASTER to implement full BUSY arbitration and width expansion. It has no internal arbitration logic and treats BUSYL/BUSYR as inputs-not outputs-so it cannot function autonomously in contention-aware systems. The 71421SA35PF8 relies entirely on external BUSY assertion from the MASTER for write-inhibit control.

What is the exact function of the BUSY pins on 71421SA35PF8?

On the 71421SA35PF8, both BUSYL and BUSYR are dedicated inputs-not outputs-that must be driven LOW by an external MASTER (e.g., IDT71321) to inhibit writes on the corresponding port. When either BUSY pin is LOW, the device internally blocks write operations regardless of R/W or CE state. This is a hardwired hardware arbitration mechanism, not a status flag.

Can 71421SA35PF8 be used without interrupt functionality?

Yes. The interrupt flags (INTL and INTR) are optional features tied to fixed addresses 7FE_H and 7FF_H. If unused, those locations function as ordinary SRAM cells. No configuration register or strap pin disables interrupts-the feature is inherently enabled by address decoding, but remains inert unless cross-port writes occur to those specific addresses.

Does 71421SA35PF8 support battery backup operation?

No. Battery backup with 2 V data retention is exclusive to LA-suffix variants (e.g., 71421LA35PF8). The 71421SA35PF8 is the standard-power version and requires continuous 5 V supply for operation and data retention; it draws up to 80 mA active current and has no low-voltage retention mode.

What package and pin count does 71421SA35PF8 use?

71421SA35PF8 uses a 64-pin TQFP package (PNG64), measuring 14 mm × 14 mm with 0.5 mm lead pitch and an exposed thermal pad. This matches the pinout shown in Figure 3 of datasheet DSC-2691/17 and is distinct from the 52-pin PLCC/STQFP variants offered in the same family.