Renesas 70261S55PF8

Overview

70261S55PF8 from IDT is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, operating at 55 ns max access time (commercial grade), supporting simultaneous asynchronous reads/writes on independent left/right ports, and used in real-time interprocessor communication systems requiring deterministic arbitration.

For engineers reviewing the 70261S55PF8 datasheet, 70261S55PF8 pinout, 70261S55PF8 application, or 70261S55PF8 equivalent, key selection criteria include port-to-port BUSY arbitration timing (tBDD ≤ 40 ns), interrupt flag behavior (INTL/INTR set/clear via dedicated addresses 3FFE/3FFF), TTL-compatible 5V ±10% supply, and 100-pin TQFP package with separate upper/lower byte enables.

Technical Context

The 70261S55PF8 implements fully asynchronous dual-port architecture with on-chip hardware arbitration: BUSY flags are generated when both ports access identical addresses, with priority determined by input stability timing (tAPS = 5 ns). It supports MASTER/SLAVE cascading via M/S pin to expand data width beyond 16 bits without external logic.

Interrupt signaling uses dedicated mailbox addresses (3FFE for INTL, 3FFF for INTR), while eight semaphore flags-addressed by A0–A2-are accessed via SEM control with CE = VIH, enabling mutual exclusion in multi-processor environments. All I/Os are TTL-compatible with push-pull BUSY/INT outputs.

Key Specifications

Pinout & Package

70261S55PF8 is housed in a 100-pin TQFP (PNG100) with 0.5 mm pitch, body size 14 mm × 14 mm × 1.4 mm. All VCC and GND pins must be connected per datasheet layout guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C028V-55AXC and IDT70V261S55PF8, the 70261S55PF8 uniquely delivers full 5V TTL compatibility, integrated semaphore hardware, and commercial-grade 55 ns timing in one package - making it optimal for legacy 5V interprocessor links where firmware relies on hardware semaphores.

Availability

70261S55PF8 is available at Aetrix Electronics and suitable for real-time interprocessor communication, digital signal processing subsystems, and industrial motion controllers requiring stable component supply and long-term obsolescence management.

Supply support for 70261S55PF8 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

IDT (Integrated Device Technology) was a fabless semiconductor company specializing in timing, memory, and interface ICs before its acquisition by Renesas in 2019. Known for high-performance SRAMs and clock solutions.

The IDT70261 product line was designed specifically for deterministic, low-latency interprocessor communication in embedded control and signal processing systems - emphasizing hardware arbitration, interrupt mailboxes, and seamless bus expansion.

FAQ

What is the maximum access time specification for the 70261S55PF8?

The 70261S55PF8 has a maximum access time of 55 ns under commercial temperature conditions (0°C to +70°C), specified as tAA, tACE, and tABE in the datasheet. This value applies to address, chip enable, and byte enable propagation delays - defining the minimum read cycle time (tRC = 55 ns) for guaranteed valid data output.

Does the 70261S55PF8 support true simultaneous access to the same memory location?

Yes, the 70261S55PF8 implements true dual-port memory cells that permit simultaneous reads or writes to the same address. When contention occurs, on-chip arbitration asserts BUSY on the lower-priority port, allowing the higher-priority access to complete - ensuring data integrity without external logic.

How does the interrupt functionality work on the 70261S55PF8?

The 70261S55PF8 uses dedicated SRAM addresses 3FFE (for INTL) and 3FFF (for INTR) as interrupt mailboxes. Writing to 3FFF sets INTR; reading 3FFF clears it. Similarly, writing to 3FFE sets INTL; reading 3FFE clears it. Both flags are push-pull outputs, eliminating need for external pull-ups.

Can the 70261S55PF8 be used in MASTER/SLAVE configurations for wider data buses?

Yes, the 70261S55PF8 supports MASTER/SLAVE cascading via the M/S pin. When M/S = H, BUSY is an output (master); when M/S = L, BUSY is an input (slave). Multiple devices can be combined to build 32-bit or wider memory systems without additional discrete logic - maintaining full-speed operation.

What are the power consumption characteristics of the 70261S55PF8 in standby mode?

In full standby (ISB3), with both ports disabled and all inputs at CMOS levels, the 70261S55PF8 draws just 1.0 mA typical. With TTL-level inputs active (ISB1), standby current rises to 13 mA typical. These low values enable energy-efficient operation in systems requiring rapid wake-up from idle states.