Renesas 71321LA55PFI8

Overview

IDT71321LA55PFI8 from Integrated Device Technology (IDT) 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 55 ns max read/write cycle time, operates on single 5V ±10% supply, supports industrial temperature range (–40°C to +85°C), and enables battery-backed data retention at 2V - used in dual-CPU arbitration, shared memory buffers, and real-time control subsystems.

For engineers reviewing the IDT71321LA55PFI8 datasheet, IDT71321LA55PFI8 pinout, IDT71321LA55PFI8 application, or IDT71321LA55PFI8 equivalent, key selection criteria include its master-mode BUSY arbitration, dual-interrupt flag behavior (INTL/INTR), 2V data retention capability, 64-pin TQFP package compatibility, and strict timing constraints for port-to-port contention resolution.

Technical Context

The IDT71321LA55PFI8 implements fully asynchronous dual-port access with independent left/right address, control, and I/O buses. Its on-chip arbitration logic resolves simultaneous accesses using address- and CE-based BUSY assertion, with tAPS = 5 ns priority setup time and tBDD ≤ 50 ns disable-to-valid-data delay.

As a MASTER-only device, it features open-drain BUSYL/BUSYR outputs requiring 270 Ω pull-ups, two dedicated interrupt flags (INTL asserted on right-port write to 7FEh, INTR on left-port write to 7FFh), and automatic power-down via CE-controlled standby modes - ISB3 ≤ 5 µA (full CMOS standby) and ICC ≤ 155 mA (both ports active at fMAX).

Key Specifications

Pinout & Package

Package: 64-pin TQFP (PNG64), 14 mm × 14 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 CY7C1371BV33-167AXC and IDT71421LA55PFI8, the IDT71321LA55PFI8 uniquely integrates master arbitration, dual interrupts, and 2V retention in a single 5V device - making it irreplaceable for cost-sensitive, low-latency interprocessor communication where external logic must be minimized.

Availability

IDT71321LA55PFI8 is available at Aetrix Electronics and suitable for real-time dual-processor communication, industrial Ethernet gateway buffering, and battery-backed data logging requiring stable component supply across extended product lifecycles.

Supply support for IDT71321LA55PFI8 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, designs high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

IDT71321LA55PFI8 belongs to the IDT71321/71421 dual-port SRAM family, engineered specifically for deterministic interprocessor communication in real-time embedded systems requiring hardware arbitration and low-latency message passing.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321LA55PFI8?

BUSYL and BUSYR are open-drain output signals on the IDT71321LA55PFI8 that indicate port contention - asserted low when both ports attempt simultaneous access to the same memory location. They require external 270 Ω pull-up resistors per datasheet Figure 3 and serve as hardware write-inhibit signals in MASTER/SLAVE configurations. The IDT71321LA55PFI8 uses these to resolve arbitration without software intervention.

Does the IDT71321LA55PFI8 support true dual-port read/write concurrency?

Yes - the IDT71321LA55PFI8 supports fully asynchronous, independent read and write operations on left and right ports simultaneously, provided addresses do not collide. When contention occurs, BUSY logic enforces deterministic priority based on tAPS (5 ns setup), and timing parameters like tBDD (≤50 ns) guarantee valid data recovery after arbitration. No internal serialization or clock domain crossing is required.

How does the interrupt functionality work in the IDT71321LA55PFI8?

The IDT71321LA55PFI8 implements hardware interrupts via two dedicated SRAM locations: writing to address 7FEh (hex) sets the INTL flag, and writing to 7FFh sets INTR. Each flag is cleared by reading its respective address. These are open-drain outputs requiring pull-ups, with tINS ≤ 45 ns assertion delay. The feature enables lock-free interprocessor messaging without polling - a core capability of the IDT71321LA55PFI8 in real-time systems.

Can the IDT71321LA55PFI8 operate with only one port enabled?

Yes - the IDT71321LA55PFI8 supports asymmetric operation: either port can be independently enabled or disabled using its dedicated CE and OE controls. When one port is disabled (CE = VIH), it enters standby mode with ISB2 ≤ 115 µA (TTL inputs) or ISB4 ≤ 70 µA (CMOS inputs). This allows dynamic power scaling in systems where memory bandwidth demand varies across processing domains - a verified behavior of the IDT71321LA55PFI8.

Is the IDT71321LA55PFI8 pin-compatible with faster speed grades like IDT71321LA35PFI8?

Yes - all IDT71321LA variants in the 64-pin TQFP (PNG64) package, including IDT71321LA35PFI8 and IDT71321LA55PFI8, share identical pinout, voltage, and logic-level specifications. The only difference is AC timing: the '55' grade guarantees 55 ns max access versus 35 ns for the '35' grade. System-level compatibility is maintained, allowing drop-in replacement where timing margins permit - confirmed by IDT's ordering information and package diagrams.