Renesas 71421LA25PFGI

Overview

IDT71421LA25PFGI from Integrated Device Technology (IDT) is a 2K × 8 dual-port static RAM operating as a SLAVE device in MASTER/SLAVE memory expansion configurations, supporting fully asynchronous port-to-port communication with interrupt flags (INTL/INTR) and BUSY input for arbitration. It delivers 25 ns max read cycle time, 1 µA typical standby current (at 5 V), and 2 V battery-backed data retention - used in real-time interprocessor communication buffers for industrial motion controllers and avionics data concentrators.

For engineers reviewing the IDT71421LA25PFGI datasheet, IDT71421LA25PFGI pinout, IDT71421LA25PFGI application, or IDT71421LA25PFGI equivalent, key selection criteria include SLAVE-side BUSY input timing (tWB = 0 ns), interrupt mailbox address mapping (7FEH/7FFH), dual-port arbitration compatibility with IDT71321LA25PFGI, and 64-pin TQFP package thermal performance under –40°C to +85°C industrial operation.

Technical Context

The IDT71421LA25PFGI functions exclusively as a SLAVE in MASTER/SLAVE dual-port SRAM systems: its BUSY pin is an input (not output), internally inhibiting writes when asserted low, and it lacks on-chip arbitration logic - relying entirely on the MASTER (e.g., IDT71321) for BUSY generation. It supports independent left/right port access with separate CE/OE/R/W controls and full TTL compatibility at 5 V ±10%.

Interrupt functionality uses fixed mailbox addresses: INTL asserts when right port writes to 7FEH; INTR asserts when left port writes to 7FFH. Both flags are cleared by reading the same address with OE/CE active. Data retention at 2 V is guaranteed only for LA versions, with ICCDR ≤ 100 µA (typ) and tCDR = 0 ns (chip deselect to retention mode).

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 CY7C024AV-25AXC and NV25024, the IDT71421LA25PFGI uniquely delivers 5 V-compatible SLAVE-side BUSY input timing, hardware interrupt mailboxes, and industrial-grade 2 V data retention - making it irreplaceable in deterministic real-time dual-CPU architectures requiring zero-software arbitration.

Availability

IDT71421LA25PFGI is available at Aetrix Electronics and suitable for industrial motion controllers, avionics data concentrators, and railway signaling interlockers requiring stable component supply across extended product lifecycles and harsh environmental conditions.

Supply support for IDT71421LA25PFGI 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.

IDT71421LA25PFGI belongs to the 71421LA family of dual-port SRAMs engineered specifically for deterministic interprocessor communication in safety-critical and real-time embedded systems - emphasizing low-latency arbitration, interrupt-driven messaging, and robust industrial operation.

FAQ

What is the role of IDT71421LA25PFGI in a MASTER/SLAVE dual-port SRAM configuration?

IDT71421LA25PFGI functions exclusively as the SLAVE device: its BUSYL and BUSYR pins are inputs (not outputs), used to inhibit writes when asserted low by the MASTER (e.g., IDT71321). It contains no internal arbitration logic and relies entirely on the MASTER for BUSY generation and priority resolution - a hardwired architectural constraint confirmed in Functional Block Diagram and Truth Table III.

Does IDT71421LA25PFGI support battery backup, and what are the retention specifications?

Yes - IDT71421LA25PFGI supports 2 V data retention, a defining feature of the "LA" suffix. Per Table 6, VDR = 2.0 V min, with ICCDR ≤ 100 µA (typ) at TA = +25°C. Retention is guaranteed but not production-tested; tCDR = 0 ns means retention mode activates immediately upon chip deselect (CE = VIH) at 2 V.

How are the interrupt flags INTL and INTR triggered and cleared on IDT71421LA25PFGI?

INTL is asserted when the right port writes to address 7FEH (per Truth Table II); INTR is asserted when the left port writes to 7FFH. Both flags are cleared by reading the same address with OE/CE active (e.g., INTL cleared by left-port read of 7FEH with CEL = OEL = VIH). Timing is bounded by tINS/tINR ≤ 25 ns (max) at 25 ns speed grade.

What package and pin count does IDT71421LA25PFGI use, and are all power pins required?

IDT71421LA25PFGI uses a 64-pin TQFP (PNG64) package. Four VCC pins (33, 47, 48, 64) and four GND pins (32, 46, 51, 63) must all be connected - explicitly mandated in Pin Configuration Notes 1 and 2. Failure to connect all VCC/GND pins risks timing violations and increased EMI per layout guidelines.

Can IDT71421LA25PFGI operate as a standalone dual-port RAM without a MASTER device?

No - IDT71421LA25PFGI lacks on-chip arbitration logic and BUSY output capability. As stated in the Description section, it is "designed to be used as a SLAVE Dual-Port" only. Using it standalone would disable BUSY-based write protection and interrupt synchronization; proper operation requires pairing with IDT71321 (MASTER) per the Width Expansion with Busy Logic section.