Renesas 71421LA55PF8

Overview

IDT71421LA55PF8 from Integrated Device Technology (IDT) is a high-speed 2K × 8 dual-port static RAM configured as a SLAVE device in MASTER/SLAVE memory expansion systems, supporting asynchronous port-to-port communication with BUSY input and interrupt flags (INTL/INTR). It delivers 55 ns max read cycle time, 2V data retention in battery backup mode, and operates on single 5V ±10% supply across –40°C to +85°C industrial temperature range - used in real-time interprocessor messaging and redundant control subsystems.

For engineers reviewing the IDT71421LA55PF8 datasheet, IDT71421LA55PF8 pinout, IDT71421LA55PF8 application, or IDT71421LA55PF8 equivalent, key selection considerations include its SLAVE-only BUSY input behavior, 2V data retention capability, 55 ns timing grade, 64-pin TQFP package, and compatibility with IDT71321 MASTER devices for 16-bit+ bus width expansion.

Technical Context

The IDT71421LA55PF8 implements fully asynchronous dual-port architecture with independent left/right address, control, and I/O buses. Its BUSY pin functions strictly as an input (not output), enabling hardware write-inhibit arbitration when paired with IDT71321 MASTER devices - critical for contention-free 16-bit memory expansion without external logic.

It supports interrupt-driven interprocessor communication via dedicated mailbox addresses (7FEh for INTL, 7FFh for INTR), with interrupt set/reset timing specified at ≤45 ns. The LA variant provides true 2V data retention with ≤4 mA full-standby current (ISB3), distinguishing it from SA versions lacking battery backup.

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 CY7C1371DV33-166AXC, IDT71421LA55PF8 offers integrated hardware arbitration and 2V data retention but requires 5V supply; compared with IDT71321LA55PF8, it lacks on-chip arbitration and serves only as SLAVE - making them complementary, not interchangeable.

Availability

IDT71421LA55PF8 is available at Aetrix Electronics and suitable for real-time interprocessor messaging, redundant control subsystems, and 16-bit bus width expansion requiring stable component supply, long-term lifecycle support, and industrial-grade reliability.

Supply support for IDT71421LA55PF8 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.

IDT71421LA55PF8 belongs to the IDT71321/71421 dual-port SRAM family, engineered specifically for deterministic interprocessor communication and hardware-arbitrated memory expansion in safety-critical and real-time embedded systems.

FAQ

What is the role of IDT71421LA55PF8 in a MASTER/SLAVE dual-port SRAM configuration?

IDT71421LA55PF8 functions exclusively as a SLAVE device: its BUSY pins (BUSYL/BUSYR) are inputs - not outputs - and must be driven low by an IDT71321 MASTER to inhibit concurrent writes during address contention. It lacks on-chip arbitration logic, relying entirely on the MASTER for BUSY generation and priority resolution. This architecture eliminates external arbitration components in 16-bit+ memory expansions.

Does IDT71421LA55PF8 support battery backup operation, and what voltage is required?

Yes, IDT71421LA55PF8 supports battery backup operation with guaranteed data retention down to 2.0 V (VDR), as confirmed in Table 6 of the datasheet. At VCC = 2.0 V and TA = +25°C, it draws ≤1500 µA (commercial) or ≤4000 µA (industrial) in retention mode. This enables use with standard lithium coin cells or supercapacitors for extended hold-up time during main power loss.

How do the interrupt flags (INTL and INTR) operate on IDT71421LA55PF8?

INTL is asserted when the right port writes to address 7FEh; INTR is asserted when the left port writes to 7FFh - per Truth Table II. Both are open-drain outputs requiring external pull-up resistors. Clearing is performed by reading the same address (7FEh for INTL, 7FFh for INTR) with OE and CE active. Interrupt timing (tINS/tINR) is ≤45 ns max for the 55 ns speed grade, ensuring low-latency interprocessor signaling.

What package and pin count does IDT71421LA55PF8 use, and is it RoHS-compliant?

IDT71421LA55PF8 uses a 64-pin TQFP package (PNG64), measuring 14 mm × 14 mm × 1.4 mm. It is lead-free and RoHS-compliant, as confirmed in the "Green parts available" note on page 1 and ordering information in the datasheet. Pin assignments match the 64-pin TQFP diagram on page 3 (Figure 71321/421 PNG64/PPG64).

Can IDT71421LA55PF8 operate independently, or must it always be paired with IDT71321?

IDT71421LA55PF8 can operate independently as a standalone 2K × 8 dual-port SRAM - all control, address, and I/O functions work without a MASTER. However, its BUSY pins remain inputs and must be held high (e.g., via pull-up) if unused; they provide no arbitration benefit alone. Pairing with IDT71321 is required only when implementing hardware-arbitrated width expansion or shared-memory contention avoidance.