Renesas 71421LA35PF

Overview

IDT71421LA35PF 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 flag logic. It delivers 35 ns max read cycle time, 2V data retention in battery backup mode, and operates on a single 5V ±10% supply across –40°C to +85°C industrial temperature range. It is used in real-time interprocessor communication buffers for industrial motion controllers.

For engineers reviewing the 71421LA35PF datasheet, 71421LA35PF pinout, 71421LA35PF application, or 71421LA35PF equivalent, this page provides verified functional role, validated timing parameters, confirmed package mapping (64-pin TQFP), and authoritative alternative part guidance - all derived from IDT's official DSC-2691/17 datasheet and ordering documentation.

Technical Context

The 71421LA35PF functions exclusively as a SLAVE dual-port SRAM: its BUSY pin is an input (not output), enabling write-inhibit arbitration when paired with a MASTER IDT71321; it lacks on-chip arbitration logic and relies on external BUSY assertion from the MASTER. Its interrupt logic responds to writes at dedicated mailbox addresses (7FE_H for INTL, 7FF_H for INTR), with interrupt set/reset times of ≤25 ns (tINS/tINR).

It supports full asynchronous operation per port, with independent CE/OE/R/W controls, and implements automatic power-down via CE-driven standby modes - achieving 1 mA typical full-standby current (ISB3) and 200 µW battery backup consumption at 2V. All I/Os are TTL-compatible with V_OH ≥2.4 V and V_OL ≤0.4 V under load.

Key Specifications

Pinout & Package

71421LA35PF is packaged in a 64-pin TQFP (PNG64) with 0.5 mm pitch, body size 14 mm × 14 mm × 1.4 mm. Pin assignments are identical to IDT71421SA/LA family specification per DSC-2691/17 Figure 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-35AXC and IS61LV25616AL-10TLI, the 71421LA35PF uniquely integrates SLAVE-mode BUSY input and mailbox interrupts in a 5V industrial-grade package - making it irreplaceable for legacy 5V MASTER/SLAVE memory expansion without redesigning arbitration or power architecture.

Availability

71421LA35PF is available at Aetrix Electronics and suitable for industrial motion controllers, redundant PLC modules, and automotive ADAS sensor hubs requiring stable component supply, long-term lifecycle assurance, and guaranteed industrial temperature compliance.

Supply support for 71421LA35PF 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.

The IDT71421LA series was engineered specifically for robust, low-latency interprocessor communication in harsh industrial environments - emphasizing hardware arbitration, battery-backed data integrity, and seamless 5V system integration.

FAQ

What is the exact memory configuration and bus width capability of the 71421LA35PF?

The 71421LA35PF is a 2K × 8 (16,384-bit) dual-port static RAM with two independent 8-bit bidirectional data buses (I/O0L–I/O7L and I/O0R–I/O7R). As a SLAVE device, it is designed to pair with a MASTER IDT71321 to construct 16-bit-or-wider memory systems without external logic - the 71421LA35PF contributes its full 8-bit width to the expanded bus under BUSY-controlled arbitration.

Does the 71421LA35PF support battery backup operation, and what voltage is required?

Yes, the 71421LA35PF supports battery backup operation with guaranteed data retention at V_CC = 2.0 V minimum (per DSC-2691/17 Table 6). This allows the device to maintain stored data during main power loss - a key requirement for preserving control state in industrial and medical systems. The typical data retention current is 100 µA at 2V and +25°C.

How does the BUSY functionality work on the 71421LA35PF, and is it compatible with the IDT71321 MASTER?

The 71421LA35PF has BUSYL and BUSYR as dedicated inputs - not outputs - and is designed exclusively as a SLAVE. When the MASTER IDT71321 detects address contention, it asserts BUSY on the corresponding line; the 71421LA35PF then inhibits writes on that port. This hardware handshake is fully compatible and requires no firmware intervention - the 71421LA35PF datasheet explicitly defines this behavior in Truth Table XIV and Functional Description Section.

What are the interrupt mailbox addresses for the 71421LA35PF, and how are they cleared?

The 71421LA35PF uses address 7FE_H to set the left-port interrupt flag (INTL) upon write from the right port, and 7FF_H to set the right-port flag (INTR) upon write from the left port. To clear INTL, the left port performs a read or write to 7FE_H with CEL = OEL = VIL; to clear INTR, the right port accesses 7FF_H with CER = OER = VIL - both operations are defined in Truth Table XIII of the 71421LA35PF datasheet.

Which package and pinout does the 71421LA35PF use, and is it pin-compatible with other speed grades?

The 71421LA35PF uses a 64-pin TQFP (PNG64) package with 0.5 mm pitch and 14 mm × 14 mm body size, matching the pinout shown in Figure 3 of DSC-2691/17. All speed variants (20/25/35/55 ns) and versions (SA/LA) in the IDT71421 family share identical pinouts and package footprints - enabling drop-in replacement across performance grades without PCB revision.