Renesas 71321LA20PFG8

Overview

IDT71321LA20PFG8 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 20 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 with independent left/right control, address, and I/O buses - deployed in motor control co-processor interfaces and industrial PLC memory buffers.

For engineers reviewing the IDT71321LA20PFG8 datasheet, IDT71321LA20PFG8 pinout, IDT71321LA20PFG8 application, or IDT71321LA20PFG8 equivalent, key selection considerations include its MASTER-only BUSY output behavior, 2V data retention capability, 52-pin STQFP package footprint, and interrupt mailbox addressing at 7FEH/7FFH - all critical for deterministic multi-CPU shared-memory designs.

Technical Context

The IDT71321LA20PFG8 implements on-chip port arbitration logic that asserts BUSYL/BUSYR outputs when address contention occurs between ports, using chip-enable and address-match timing (tBAA ≤ 20 ns) - not R/W state - to determine priority. Its interrupt subsystem uses dedicated SRAM addresses (7FEH for INTL, 7FFH for INTR) to signal cross-port events via edge-triggered flags cleared by read access.

This device operates exclusively as a MASTER: BUSYL and BUSYR are open-drain outputs requiring 270 Ω pull-ups, while INTL and INTR are active-low interrupt flags synchronized to internal write cycles. It does not accept BUSY inputs - unlike the SLAVE IDT71421 - and lacks slave-side arbitration input functionality.

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 CY7C1371DV33-200BZI, IDT71321LA20PFG8 delivers integrated hardware arbitration and interrupt signaling at 5 V, eliminating external glue logic - whereas compared with IDT71421LA20PFG8, it provides autonomous MASTER functionality essential for standalone dual-CPU designs.

Availability

IDT71321LA20PFG8 is available at Aetrix Electronics and suitable for industrial PLCs, avionics data loggers, and medical imaging subsystems requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for IDT71321LA20PFG8 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 high-performance computing and industrial systems.

IDT71321LA20PFG8 belongs to the IDT71321/71421 dual-port SRAM family, engineered specifically for deterministic interprocessor communication in real-time embedded control applications where hardware arbitration and low-power retention are mandatory.

FAQ

What is the function of BUSYL and BUSYR on the IDT71321LA20PFG8?

BUSYL and BUSYR are open-drain arbitration outputs on the IDT71321LA20PFG8, asserted low when address contention occurs between left and right ports. They require 270 Ω pull-up resistors and serve as hardware write-inhibit signals in MASTER/SLAVE configurations. Unlike SLAVE devices, IDT71321LA20PFG8 never accepts BUSY as an input - it generates both flags internally based on CE and address timing.

Does the IDT71321LA20PFG8 support battery backup operation?

Yes, the IDT71321LA20PFG8 (LA version) supports true battery backup: it retains data at VCC = 2.0 V with typical current draw of 100 µA. This capability is confirmed in datasheet Table 6 and applies only to LA-grade parts - SA versions lack this feature. The 2V retention is guaranteed but not production-tested per specification.

How are interrupts generated and cleared in the IDT71321LA20PFG8?

Interrupts in the IDT71321LA20PFG8 are triggered by writes to dedicated mailbox addresses: right-port write to 7FEH sets INTL; left-port write to 7FFH sets INTR. Both flags are cleared by reading the same address (e.g., accessing 7FEH with CEL = OEL = VIL clears INTL). Timing is defined by tINS ≤ 20 ns and tINR ≤ 20 ns per datasheet Table 11a.

Can the IDT71321LA20PFG8 operate as a SLAVE device?

No - the IDT71321LA20PFG8 is strictly a MASTER device. Its BUSYL and BUSYR pins are outputs only, and it contains on-chip arbitration logic absent in SLAVE variants like IDT71421. Attempting to use IDT71321LA20PFG8 as a SLAVE will result in incorrect BUSY behavior and potential data corruption due to missing input-handling circuitry.

What package type is used for the IDT71321LA20PFG8?

IDT71321LA20PFG8 uses a 52-pin STQFP (Small Thin Quad Flat Package), designated PPG52 in IDT documentation. Its dimensions are 10 mm × 10 mm × 1.4 mm, with gull-wing leads and RoHS-compliant finish. This package is distinct from the 64-pin TQFP variants and requires specific PCB land patterns per IDT's mechanical drawing DSC-2691.