Renesas 70261S55PFI8

Overview

70261S55PFI8 from IDT (Integrated Device Technology) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, operating at 55 ns max access time, supporting independent asynchronous reads/writes on left and right ports, and designed for real-time inter-processor communication in embedded control systems.

For engineers reviewing the 70261S55PFI8 datasheet, 70261S55PFI8 pinout, 70261S55PFI8 application, or 70261S55PFI8 equivalent, this device delivers deterministic port arbitration, hardware semaphore signaling across two 16-bit data buses, and industrial-grade operation from –40°C to +85°C in a 100-pin TQFP package.

Technical Context

The 70261S55PFI8 implements fully asynchronous dual-port architecture with separate address, control, and I/O pins per port, enabling simultaneous non-blocking access to any memory location. Its on-chip arbitration logic resolves contention via BUSY flag assertion and supports MASTER/SLAVE cascading for 32-bit+ bus expansion.

It integrates dedicated interrupt flags (INTL/INTR) triggered by writes to fixed mailbox addresses (3FFEh/3FFFh), and eight hardware semaphores addressed via A0–A2, all accessible without external logic. Power management uses CE-controlled active/standby modes with 750 mW typical active and 5 mW typical standby current.

Key Specifications

Pinout & Package

70261S55PFI8 is housed in a 100-pin Thin Quad Flatpack (TQFP) with 0.5 mm pitch, body size 14 mm × 14 mm × 1.4 mm. All VCC and GND pins must be individually decoupled 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 CY7C1362BV33-55AXI and IS61WV102416BLL-10TLI, the 70261S55PFI8 uniquely integrates hardware arbitration, mailbox interrupts, and semaphores in a single 5 V, industrial-grade package-reducing system-level design effort, validation risk, and total cost of ownership for tightly coupled dual-processor architectures.

Availability

70261S55PFI8 is available at Aetrix Electronics and suitable for industrial motion control, avionics data exchange, medical imaging subsystems, and automotive ADAS domain controllers requiring stable component supply and long-term manufacturability.

Supply support for 70261S55PFI8 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), now part of Renesas Electronics, is a semiconductor company specializing in timing, memory interface, RF, and high-performance mixed-signal solutions for communications, computing, and industrial markets.

The IDT70261 product line was engineered specifically for deterministic inter-processor communication in real-time embedded systems-delivering hardware-accelerated synchronization primitives to replace software-based messaging stacks.

FAQ

What is the maximum guaranteed access time for the 70261S55PFI8 under industrial temperature conditions?

The 70261S55PFI8 guarantees a maximum access time of 55 ns across the full industrial temperature range (–40°C to +85°C) when operated at 5.0 V ±10%. This value is specified as tAA (Address Access Time) in the AC Electrical Characteristics table and applies to both left and right ports independently under worst-case voltage and temperature conditions.

Does the 70261S55PFI8 support true simultaneous read/write operations to the same memory address?

No-the 70261S55PFI8 does not permit simultaneous read/write to the same address without arbitration. When both ports attempt concurrent access to identical locations, its on-chip BUSY logic asserts the BUSYL or BUSYR flag to stall one port, ensuring data integrity. This behavior is documented in Truth Table IV and the BUSY Timing section of the datasheet.

How are the interrupt flags INTL and INTR triggered and cleared in the 70261S55PFI8?

The 70261S55PFI8 triggers INTL when the right port writes to address 3FFEh (with CER = R/WR = VIL), and triggers INTR when the left port writes to 3FFFh. INTL is cleared by the left port reading 3FFEh (CEL = OEL = VIL), and INTR is cleared by the right port reading 3FFFh (CER = OER = VIL). These sequences are defined in Truth Table III.

Can the 70261S55PFI8 operate with only one port enabled while the other remains inactive?

Yes-the 70261S55PFI8 supports asymmetric operation. Either port can be disabled independently via its CE pin (CEL or CER). When CE = VIH, that port enters standby mode drawing only 5 mW (typ.), while the other port remains fully functional with full 55 ns access performance and uninterrupted interrupt/semaphore operation.

What is the function of the M/S pin on the 70261S55PFI8, and how does it affect BUSY behavior?

The M/S pin configures the 70261S55PFI8 as MASTER (M/S = VIH) or SLAVE (M/S = VIL). In MASTER mode, BUSYL/BUSYR are outputs that assert when address contention occurs; in SLAVE mode, they become inputs used to receive BUSY signals from a master device in cascaded configurations-enabling scalable multi-chip memory expansion without external arbitration logic.