Renesas 70261L55PF8

Overview

70261L55PF8 from IDT (Integrated Device Technology) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore support, operating at 55 ns max access time in commercial temperature range (0°C to +70°C), powered by single 5V ±10% supply, and featuring independent left/right ports with full asynchronous operation for real-time inter-processor communication.

For engineers reviewing the 70261L55PF8 datasheet, 70261L55PF8 pinout, 70261L55PF8 application, or 70261L55PF8 equivalent, this device is selected for deterministic memory arbitration in dual-CPU systems, mailbox-based IPC, hardware semaphore coordination, and low-latency shared-memory architectures where simultaneous port access and BUSY/INT flag signaling are required.

Technical Context

The 70261L55PF8 implements fully asynchronous dual-port architecture with on-chip arbitration logic that resolves contention via BUSY flag assertion-either through address match detection (M/S = VIH) or chip-enable timing priority (M/S = VIL). It supports two distinct memory access modes: standard RAM read/write (CE = VIL, SEM = VIH) and semaphore register access (CE = VIH, SEM = VIL), with eight dedicated semaphore flags addressed by A0–A2.

Interrupt functionality uses fixed mailbox addresses: INTL asserts when right port writes to 3FFE_H; INTR asserts when left port writes to 3FFF_H. Both ports support separate upper-byte (UB/UBR) and lower-byte (LB/LBR) control, enabling multiplexed bus compatibility and seamless 32-bit expansion via MASTER/SLAVE cascading using M/S pin configuration.

Key Specifications

Pinout & Package

70261L55PF8 is housed in a 100-pin Thin Quad Flatpack (TQFP) with exposed thermal pad, requiring all VCC and GND pins to be connected per layout guidelines. Pin functions are strictly segregated between left port (L-suffixed) and right port (R-suffixed) I/O, control, and address groups.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV33-55AXI, 70261L55PF8 delivers integrated hardware arbitration and mailbox interrupts in a 5V system, reducing design risk and component count; versus IDT70V261S15PFI, it trades speed and temperature range for ultra-low 1 µA standby current-ideal for power-sensitive commercial applications.

Availability

70261L55PF8 is available at Aetrix Electronics and suitable for real-time inter-processor communication, telecom line card buffering, dual-CPU embedded control systems, avionics data concentrators, and industrial PLC architectures requiring stable component supply and long-term obsolescence management.

Supply support for 70261L55PF8 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 high-performance timing, memory interface, and RF solutions before its acquisition by Renesas Electronics in 2019. Its dual-port SRAM portfolio emphasized deterministic latency and hardware coherency.

The IDT70261 family was designed specifically for deterministic shared-memory systems requiring zero-software-overhead inter-processor coordination, targeting telecom infrastructure, industrial automation, and aerospace data handling subsystems.

FAQ

What is the maximum access time specification for the 70261L55PF8?

The 70261L55PF8 has a maximum address access time (tAA) of 55 ns under commercial temperature conditions (0°C to +70°C) and VCC = 5.0 V ±10%. This value is guaranteed across the full operating voltage and temperature range and reflects worst-case delay from stable address to valid data output on an enabled port. The 55 ns rating applies to both left and right ports independently.

Does the 70261L55PF8 support true simultaneous access to the same memory location?

Yes, the 70261L55PF8 implements true dual-port memory cells that permit simultaneous read/write access to identical addresses. When contention occurs, on-chip arbitration logic asserts the BUSY flag on the losing port to stall access, ensuring deterministic resolution without data corruption. This behavior is confirmed in Truth Table IV and timing waveforms on pages 13–14 of the datasheet.

How does the interrupt functionality work on the 70261L55PF8?

The 70261L55PF8 uses fixed-address mailboxes: writing to address 3FFF_H via the left port asserts the INTR flag on the right port; writing to 3FFE_H via the right port asserts the INTL flag on the left port. Clearing is symmetric-reading 3FFF_H clears INTR, reading 3FFE_H clears INTL. These operations require proper CE and R/W control per Truth Table III.

What is the standby current consumption of the 70261L55PF8?

The 70261L55PF8 achieves 1 µA typical full-standby current (ISB3) when both CEL and CER are held high, all inputs are at rail extremes (VCC − 0.2 V or < 0.2 V), and SEMR/SEML are high. This ultra-low quiescent draw supports energy-sensitive applications such as always-on communication gateways and battery-buffered control modules.

Can the 70261L55PF8 be used in a 32-bit memory system?

Yes, the 70261L55PF8 supports 32-bit expansion via MASTER/SLAVE cascading. When configured as MASTER (M/S = H), BUSY is an output; as SLAVE (M/S = L), BUSY is an input. Multiple devices can be stacked using the BUSY signal to coordinate access, enabling full-speed, error-free 32-bit-or-wider word systems without external glue logic.