Renesas 71421LA20PF

Overview

71421LA20PF from Integrated Device Technology is a 2K × 8 dual-port static RAM configured as a SLAVE device in MASTER/SLAVE memory expansion systems, featuring interrupt flags (INTL/INTR), BUSY input for write arbitration, 20 ns read cycle time (commercial grade), 5 V ±10% supply, and 2 V battery-backed data retention. It enables error-free 16-bit-or-wider memory systems without external logic in industrial controllers and real-time interprocessor communication.

For engineers reviewing the 71421LA20PF datasheet, 71421LA20PF pinout, 71421LA20PF application, or 71421LA20PF equivalent, key selection criteria include its SLAVE-only BUSY input behavior, 1 mW standby power, 20 ns tRC timing, 64-pin TQFP package, and compatibility with IDT71321SA/LA MASTER devices in width-expanded architectures.

Technical Context

The 71421LA20PF operates as a SLAVE dual-port SRAM with dedicated BUSY input (not output) to receive arbitration signals from a MASTER IDT71321 device; it lacks on-chip arbitration logic and relies entirely on external BUSY assertion to inhibit concurrent writes. Its interrupt functionality uses fixed mailbox addresses (7FE_H for INTL, 7FF_H for INTR) with set/reset controlled by port-specific write patterns.

It supports fully asynchronous, independent access on left (L) and right (R) ports - each with separate address (A0–A10), control (CEL/CER, OEL/OER, R/WL/R/WR), and bidirectional I/O (I/O0–I/O7) - and implements automatic power-down via CE-driven low-power modes, including full standby at 0.2 mA (typ.) under CMOS-level inputs.

Key Specifications

Pinout & Package

71421LA20PF is packaged in a 64-pin TQFP (PNG64) with 0.5 mm pitch, 14 mm × 14 mm body, and exposed thermal pad. Pin functions are asymmetric: left-port signals (e.g., A0L–A10L, I/O0L–I/O7L, CEL, OEL, R/WL) occupy one side; right-port signals (A0R–A10R, I/O0R–I/O7R, CER, OER, R/WR) occupy the opposite side; BUSYR and BUSYL are dedicated inputs (not outputs), and INTL/INTR are open-drain interrupt flags requiring external pull-ups.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-20AXC, 71421LA20PF offers lower system-level power (0.2 mA ISB3 vs. 1.5 mA) and battery retention, but requires a MASTER partner; compared with IDT71321LA20PF, it provides SLAVE-specific BUSY input behavior essential for deterministic arbitration in multi-device configurations.

Availability

71421LA20PF is available at Aetrix Electronics and suitable for industrial PLC memory expansion, real-time interprocessor communication, and embedded data loggers requiring stable component supply, long-term lifecycle support, and guaranteed commercial-grade timing performance.

Supply support for 71421LA20PF 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 IDT71421 product line delivers dual-port SRAMs optimized for deterministic interprocessor communication and memory expansion in real-time embedded systems, emphasizing hardware arbitration, low-power retention, and seamless MASTER/SLAVE interoperability.

FAQ

What is the role of 71421LA20PF in a MASTER/SLAVE dual-port SRAM configuration?

The 71421LA20PF serves exclusively as the SLAVE device: it accepts BUSYR/BUSYL inputs from a MASTER IDT71321 to inhibit concurrent writes during address contention, lacks on-chip arbitration logic, and relies on external BUSY signaling for safe width expansion. It cannot function as a standalone MASTER.

Does 71421LA20PF support battery backup, and what voltage is required?

Yes, the LA suffix indicates battery backup capability: 71421LA20PF retains data at VCC = 2.0 V minimum, drawing ≤100 µA typical (up to 1500 µA max) in data retention mode. This enables nonvolatile storage during main power loss in portable or safety-critical systems.

How are interrupts generated and cleared on 71421LA20PF?

71421LA20PF uses fixed SRAM addresses for interrupts: writing to 7FE_H sets INTL (left port flag); writing to 7FF_H sets INTR (right port flag). Clearing requires reading those same addresses with OE and CE asserted - no dedicated control registers or commands are needed.

What package and pin count does 71421LA20PF use, and are pinouts compatible with other IDT dual-port SRAMs?

71421LA20PF uses a 64-pin TQFP (PNG64) package with 0.5 mm pitch. Its pinout matches IDT71321LA20PF in signal placement (e.g., A0L–A10L on same pins), enabling direct PCB layout reuse in MASTER/SLAVE pairs - though BUSY pins are inputs here versus outputs on the MASTER.

Can 71421LA20PF operate in industrial temperature range (–40°C to +85°C)?

No - the "20" speed grade (20 ns tRC) is specified for commercial temperature range only (0°C to +70°C). For industrial operation, select 71421LA25PF (25 ns) or 71421LA55PF (55 ns), which are explicitly rated for –40°C to +85°C per datasheet Table 2.