Renesas 71321SA35PF8

Overview

71321SA35PF8 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 systems. It supports 35 ns max read cycle time, operates on single 5V ±10% supply, features two independent asynchronous ports (left/right), and delivers 80 mA typical dynamic current at f_MAX. It is used in real-time embedded control systems requiring concurrent CPU and DSP access to shared memory.

For engineers reviewing the 71321SA35PF8 datasheet, 71321SA35PF8 pinout, 71321SA35PF8 application, or 71321SA35PF8 equivalent, key selection criteria include its MASTER-only BUSY output capability, interrupt mailbox addressing (7FE_H/7FF_H), 52-pin STQFP package, industrial temperature support (–40°C to +85°C), and compatibility with IDT71421 SLAVE devices for 16-bit+ width expansion.

Technical Context

The 71321SA35PF8 implements on-chip port arbitration logic that asserts BUSYL/BUSYR outputs based solely on chip enable (CEL/CER) and address match timing-regardless of R/W state-enabling deterministic contention resolution between asynchronous processors. Its interrupt subsystem uses dedicated SRAM addresses (7FE_H for INTL, 7FF_H for INTR) to signal cross-port events without software polling.

It supports fully independent left/right port operation with separate control (CEL/OEL/R/WL and CER/OER/R/WR), address (A0L–A10L / A0R–A10R), and bidirectional I/O (I/O0L–I/O7L / I/O0R–I/O7R) pins. The BUSY outputs are open-drain and require external 270 Ω pull-up resistors per datasheet Note 1 and Figure 3.

Key Specifications

Pinout & Package

71321SA35PF8 is packaged in a 52-pin STQFP (PPG52), measuring 10 mm × 10 mm × 1.4 mm, with exposed thermal pad (not electrically connected). Pin 1 is located at bottom-left corner when notch faces up; all VCC pins (e.g., pins 18, 27, 40, 49) must be decoupled locally; all GND pins (e.g., pins 26, 33, 46) require low-inductance ground plane connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-35AXC and IDT71421SA35PF8, the 71321SA35PF8 uniquely integrates MASTER arbitration and interrupt mailboxes in a 2K × 8 configuration-enabling deterministic real-time interprocessor communication without external components or software overhead.

Availability

71321SA35PF8 is available at Aetrix Electronics and suitable for real-time motion control, digital signal processing interfaces, redundant controller communication, and industrial Ethernet gateway applications requiring stable component supply and long-term industrial-grade availability.

Supply support for 71321SA35PF8 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 power management ICs for communications, computing, and industrial markets.

The IDT71321 product line was engineered specifically for deterministic interprocessor communication in hard real-time embedded systems-delivering hardware-enforced arbitration, low-latency interrupts, and seamless MASTER/SLAVE scalability without external logic.

FAQ

What is the function of the BUSY pins on the 71321SA35PF8?

The BUSYL and BUSYR pins on the 71321SA35PF8 are open-drain outputs that signal port contention when both ports attempt simultaneous access to the same memory location. As a MASTER device, the 71321SA35PF8 asserts BUSY to inhibit writes on the contending port-preventing data corruption without software intervention. Each BUSY pin requires a 270 Ω external pull-up resistor per datasheet Figure 3 and Note 1.

How does the interrupt functionality work in the 71321SA35PF8?

The 71321SA35PF8 uses dedicated SRAM addresses 7FE_H and 7FF_H as hardware interrupt mailboxes: writing to 7FE_H from the right port sets INTL, while writing to 7FF_H from the left port sets INTR. Clearing occurs when the respective port reads that address with CE and OE asserted. This enables zero-software-overhead event signaling-critical for real-time response in applications like motion control where the 71321SA35PF8 is deployed.

Can the 71321SA35PF8 operate as a standalone dual-port RAM without a SLAVE device?

Yes, the 71321SA35PF8 functions fully as a standalone 2K × 8 dual-port SRAM with complete left/right port independence, interrupt generation, and BUSY arbitration. Its MASTER designation means it contains on-chip arbitration logic and BUSY outputs-unlike SLAVE-only parts such as IDT71421SA35PF8. No companion device is required unless expanding data width beyond 8 bits, in which case one or more SLAVE units may be added.

What is the significance of the 'SA' suffix in 71321SA35PF8?

'SA' denotes the standard-power version of the IDT71321 family, distinguishing it from the low-power 'LA' variant. The 71321SA35PF8 draws 80 mA typical dynamic current and 25 mA typical standby current (ISB1), optimized for performance-critical applications where speed takes priority over ultra-low quiescent power. It does not support battery backup data retention-unlike LA versions, which guarantee 2V data retention.

Which package type does the 71321SA35PF8 use, and what are its board-level implications?

The 71321SA35PF8 uses a 52-pin STQFP (PPG52) package: 10 mm × 10 mm × 1.4 mm with gull-wing leads and an exposed thermal pad. Its compact footprint suits high-density industrial PCBs; the four VCC and three GND pins enable robust power delivery; and the absence of lead-free exemptions simplifies RoHS-compliant assembly. Layout best practices include 20-mil trace widths for I/Os, 100-nF ceramic decoupling per VCC pin, and solid ground plane under the thermal pad.