Renesas 71321SA20TF

Overview

IDT71321SA20TF from Integrated Device Technology (IDT) is a high-speed 2K × 8 dual-port static RAM with on-chip interrupt logic and BUSY arbitration, designed as a MASTER device for interprocessor communication. It delivers 20 ns max read cycle time, operates at 5V ±10%, supports industrial temperature range (–40°C to +85°C), and features open-drain BUSY/INT outputs requiring 270Ω pull-up resistors - used in real-time embedded control systems where deterministic port arbitration is critical.

For engineers reviewing the 71321SA20TF datasheet, 71321SA20TF pinout, 71321SA20TF application, or 71321SA20TF equivalent, this page provides verified functional identity, validated pin roles, confirmed timing parameters (tRC = 20 ns, tAA = 20 ns), exact package mapping (64-pin TQFP), and two technically documented alternative parts for memory expansion architectures.

Technical Context

The 71321SA20TF implements fully asynchronous dual-port operation with independent left/right address, control, and I/O buses. Its on-chip arbitration logic resolves contention via BUSY flag generation based solely on chip enable (CEL/CER) and address match timing - not R/W state - ensuring deterministic write inhibition during simultaneous access to identical addresses.

As a MASTER device, it drives BUSYL and BUSYR as open-drain outputs (requiring external 270Ω pull-ups), while supporting interrupt flag generation (INTL/INTR) triggered by writes to dedicated mailbox addresses (7FEh/7FFh). It does not accept BUSY as input - that function is reserved for SLAVE IDT71421 devices.

Key Specifications

Pinout & Package

71321SA20TF is packaged in a 64-pin TQFP (PNG64) with 0.5 mm pitch, body size 14 mm × 14 mm × 1.4 mm. All VCC pins must be decoupled locally; all GND pins require low-inductance grounding.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C024AV-20AXC and IDT71421SA20TF, the 71321SA20TF uniquely integrates hardware BUSY arbitration and MASTER interrupt mailbox functionality in a 5V, 2K×8 form factor - making it irreplaceable in deterministic dual-CPU designs requiring zero-latency conflict resolution.

Availability

71321SA20TF is available at Aetrix Electronics and suitable for real-time dual-processor communication, industrial motion control buffering, and avionics data concentrator interfaces requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for 71321SA20TF 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, and RF power solutions for communications, computing, and industrial markets.

The IDT71321 family was engineered specifically for deterministic interprocessor communication in hard real-time systems - emphasizing hardware arbitration, low-latency interrupts, and seamless MASTER/SLAVE scalability without external glue logic.

FAQ

What is the function of BUSYL and BUSYR on the 71321SA20TF?

BUSYL and BUSYR are open-drain output flags on the 71321SA20TF that go low when address contention is detected between left and right ports. They serve as hardware write-inhibit signals - blocking writes on the contending port until the BUSY condition clears. External 270Ω pull-up resistors are required per datasheet specification. This behavior is exclusive to the MASTER 71321SA20TF; SLAVE devices use BUSY as an input.

Can the 71321SA20TF operate in battery backup mode?

No, the 71321SA20TF (SA suffix) does not support battery backup operation. Only LA-suffix variants (e.g., 71321LA20TF) provide 2V data retention capability. The SA version is optimized for commercial/industrial speed and power performance, with ISB1 = 30 mA typical standby current - not ultra-low-power retention mode.

How do the interrupt flags INTL and INTR work on the 71321SA20TF?

INTL is asserted when the right port writes to memory address 7FEh; INTR is asserted when the left port writes to 7FFh. Both are open-drain outputs requiring pull-ups. Clearing occurs when the respective port reads that same address with CE and OE low. The 71321SA20TF implements this entirely in hardware - no firmware intervention is needed to set or clear these flags.

Is the 71321SA20TF pin-compatible with the 71421SA20TF?

No - although both share identical pin count and footprint (64-pin TQFP), their BUSY pin functionality differs fundamentally: 71321SA20TF drives BUSYL/BUSYR as outputs, while 71421SA20TF receives them as inputs. Swapping them causes functional failure. They are complementary components in a MASTER/SLAVE pair, not pin-compatible alternatives.

What is the maximum operating frequency supported by the 71321SA20TF?

The 71321SA20TF does not specify a clock frequency; it is an asynchronous SRAM. Its performance is defined by timing parameters: tRC = 20 ns max read cycle time implies reliable operation up to 50 MHz effective bus rate (1/20 ns), assuming proper setup/hold timing for address, CE, and OE. No internal clock circuitry exists - timing is purely signal-propagation dependent.