Renesas 71321LA55TF8

Overview

IDT71321LA55TF8 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 features 55 ns max read cycle time, 2V data retention capability, industrial temperature range (–40°C to +85°C), TTL-compatible 5V ±10% supply, and supports asynchronous dual-port access without external logic. It is used in motor control co-processor memory buffers requiring deterministic port arbitration.

For engineers reviewing the IDT71321LA55TF8 datasheet, IDT71321LA55TF8 pinout, IDT71321LA55TF8 application, or IDT71321LA55TF8 equivalent, key selection criteria include BUSY output timing (tBAA ≤ 30 ns), interrupt mailbox address mapping (7FEH/7FFH), dual-port power-down current (ISB3 = 0.2 mA typ.), and 64-pin TQFP package compatibility with board-level signal integrity constraints.

Technical Context

The IDT71321LA55TF8 implements on-chip port arbitration using CE and address-match detection (tAPS = 5 ns), generating open-drain BUSY outputs that require 270 Ω pull-up resistors. Its interrupt logic uses dedicated mailbox addresses (7FEH for INTL, 7FFH for INTR) with set/reset timing tINS/tINR ≤ 45 ns (max).

It operates fully asynchronously per port, with independent CE/OE/R/W controls, and supports battery backup via 2V data retention (VDR = 2.0 V, ICCDR ≤ 4000 µA at industrial temp). The LA variant achieves full standby current ISB3 = 0.2 mA (typ.) under CMOS-level inputs.

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 CY7C1371BV33-133AXC and IDT71421LA55TF8, the IDT71321LA55TF8 uniquely integrates MASTER arbitration, interrupt mailboxes, and 2V retention in a single 5V device-making it optimal for deterministic, low-power, self-contained dual-processor memory interfaces without external glue logic.

Availability

IDT71321LA55TF8 is available at Aetrix Electronics and suitable for motor control co-processors, industrial PLC memory bridges, automotive ADAS sensor fusion hubs, and railway signaling redundancy modules requiring stable component supply across extended product lifecycles.

Supply support for IDT71321LA55TF8 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, RF, and power management ICs for communications, computing, and industrial markets.

IDT71321LA55TF8 belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic interprocessor communication in real-time embedded systems requiring hardware arbitration and low-latency interrupt signaling.

FAQ

What is the guaranteed data retention voltage for IDT71321LA55TF8?

IDT71321LA55TF8 guarantees data retention at VCC = 2.0 V (minimum), validated across the industrial temperature range (–40°C to +85°C). This enables reliable battery-backed operation during main supply interruption. The LA suffix explicitly denotes this low-voltage retention capability, unlike SA variants which lack it. Data retention current ICCDR is specified up to 4000 µA at +85°C.

How does BUSY arbitration work on IDT71321LA55TF8, and what timing parameters govern it?

IDT71321LA55TF8 implements hardware BUSY arbitration based on chip enable (CE) and address match detection. When both ports access the same address, the earlier-stable port wins; tAPS = 5 ns is the required arbitration priority setup time. BUSYL/BUSYR are open-drain outputs asserting low during contention. Critical timing includes tBAA ≤ 30 ns (BUSY access from address) and tBDD ≤ 50 ns (BUSY disable to valid data), ensuring deterministic resolution without external logic.

Can IDT71321LA55TF8 be used as a SLAVE device in a width-expanded memory array?

No. IDT71321LA55TF8 is exclusively a MASTER device: its BUSYL and BUSYR pins are open-drain outputs, and it contains on-chip arbitration logic. For SLAVE functionality-where BUSY pins serve as inputs and arbitration is delegated-the IDT71421LA55TF8 must be used. Attempting to configure IDT71321LA55TF8 as a SLAVE violates its functional specification and will result in incorrect BUSY behavior and potential data corruption.

What are the interrupt mailbox addresses for IDT71321LA55TF8, and how are they cleared?

IDT71321LA55TF8 uses fixed SRAM addresses for interrupt signaling: writing to address 7FEH (hex) asserts the left-port interrupt flag (INTL), and writing to 7FFH asserts the right-port flag (INTR). To clear INTL, the left port must perform a read or write access to 7FEH with CEL = OEL = VIH (i.e., disabled); to clear INTR, the right port accesses 7FFH under the same condition. These operations are defined in Truth Table II of the datasheet.

Is IDT71321LA55TF8 pin-compatible with faster speed grades like IDT71321LA35TF8?

Yes. All IDT71321LAxxTF8 variants-including 55 ns, 35 ns, and 25 ns versions-share identical 64-pin TQFP (PNG64) packaging, pinout, and DC characteristics. Speed grade differences affect only AC timing parameters (e.g., tRC, tAA, tINS). System designs can upgrade performance by replacing IDT71321LA55TF8 with IDT71321LA35TF8 without PCB or firmware changes, provided timing margins accommodate the faster access.