Renesas 70261L25PFI8

Overview

70261L25PFI8 from IDT (now Renesas) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, operating at 25 ns max access time over industrial temperature (–40°C to +85°C), powered by single 5V ±10% supply, and packaged in 100-pin TQFP. It enables simultaneous asynchronous read/write access from independent left/right ports - used in real-time inter-processor communication, video frame buffers, and military/aerospace avionics data exchange.

For engineers reviewing the 70261L25PFI8 datasheet, 70261L25PFI8 pinout, 70261L25PFI8 application, or 70261L25PFI8 equivalent, key selection considerations include BUSY/INT flag timing (tINS/tINR ≤ 20 ns), low standby current (ISB3 = 0.2 mA typ.), dual-port arbitration behavior under address contention, and master/slave cascading capability for 32-bit+ bus expansion.

Technical Context

The 70261L25PFI8 implements fully asynchronous dual-port architecture with separate address, control, and I/O buses per port - no clock required. Its on-chip arbitration logic resolves port-to-port contention via push-pull BUSY flags and supports both address-match and CE-controlled arbitration modes (tAPS = 5 ns setup).

It integrates eight hardware semaphores (addressed by A0–A2) accessible via dedicated SEM pin and CE/SEM polarity inversion (CE = VIH, SEM = VIL), enabling atomic resource locking between processors. Interrupt generation is memory-mapped: INTL asserts on right-port write to 0x3FFE; INTR asserts on left-port write to 0x3FFF - both cleared by corresponding port read/write.

Key Specifications

Pinout & Package

70261L25PFI8 is housed in a 100-pin Thin Quad Flatpack (TQFP) measuring 14 mm × 14 mm × 1.4 mm, with 0.5 mm pitch and exposed thermal pad (not electrically connected). All 100 pins are assigned; no NC pins except four corner pads (pins 1–4, 75–78, 97–100 as shown in pin diagram).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV33-25BGXI and IDT70V261S25PFGI, the 70261L25PFI8 uniquely delivers industrial-grade reliability, hardware semaphore support, and interrupt capability in a single 5V device - eliminating BOM count and layout complexity in safety-critical dual-CPU systems.

Availability

70261L25PFI8 is available at Aetrix Electronics and suitable for real-time inter-processor communication, avionics data exchange, and industrial PLC memory coherency requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 70261L25PFI8 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

Renesas Electronics (formerly Integrated Device Technology) is a global semiconductor leader specializing in high-performance memory, timing, and interface solutions for industrial, automotive, and communications infrastructure.

The IDT70261 family was designed specifically for deterministic, low-latency shared-memory architectures in dual-processor systems - emphasizing hardware arbitration, interrupt signaling, and seamless bus expansion without external logic.

FAQ

What is the maximum operating frequency supported by the 70261L25PFI8?

The 70261L25PFI8 does not operate on a clock; it is fully asynchronous. Its 25 ns maximum access time supports reliable operation in systems with up to 40 MHz effective bus bandwidth (tRC = 25 ns). Timing margins must be verified against actual board-level signal integrity, especially for simultaneous dual-port access where tBDD ≤ 30 ns governs valid data window after BUSY deassertion.

How does the 70261L25PFI8 handle simultaneous access to the same memory location?

The 70261L25PFI8 uses hardware BUSY arbitration: when both ports attempt access to identical addresses, the earlier port wins (determined by tAPS = 5 ns setup), and the later port's BUSY flag asserts to stall its write. Writes are internally inhibited while BUSY is active - no data corruption occurs. This behavior is guaranteed across –40°C to +85°C and requires no firmware intervention.

Can the 70261L25PFI8 be used in a 32-bit data bus configuration?

Yes. The 70261L25PFI8 supports master/slave cascading via the M/S pin: one device configured as MASTER (M/S = H) provides BUSY output, while another as SLAVE (M/S = L) accepts BUSY input. Two devices can be combined to form a 32-bit wide memory without external logic - preserving full 25 ns access speed and maintaining independent port control on both halves.

What is the purpose of the SEM pin on the 70261L25PFI8?

The SEM (Semaphore Enable) pin selects between RAM array access (SEM = VIH) and semaphore register access (SEM = VIL). When SEM = VIL and CE = VIH, the eight hardware semaphores - addressed by A0–A2 - become active. Writing to I/O0 controls token state; reading any I/O0–I/O15 returns the current semaphore value. This provides atomic, hardware-enforced resource locking without CPU intervention.

Does the 70261L25PFI8 require external pull-up resistors on INTL or INTR pins?

No. The 70261L25PFI8 features push-pull interrupt outputs (INTL and INTR), not open-drain. They actively drive HIGH or LOW without external components. VOH ≥ 2.4 V and VOL ≤ 0.4 V under 4 mA load ensure direct compatibility with standard 5V CMOS/TTL interrupt inputs - simplifying schematic design and improving noise immunity.