Renesas 70261S15PF8

Overview

70261S15PF8 from IDT (now Renesas) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, designed for real-time inter-processor communication in embedded systems. It supports simultaneous asynchronous access to the same memory location from left and right ports, features 15 ns max read cycle time (commercial grade), 5 V ±10% single-supply operation, and integrated BUSY/INT flag signaling - enabling deterministic arbitration in multi-CPU architectures such as radar signal processors and industrial PLCs.

For engineers reviewing the 70261S15PF8 datasheet, 70261S15PF8 pinout, 70261S15PF8 application, or 70261S15PF8 equivalent, key selection considerations include its 100-pin TQFP package, master/slave cascading capability for 32-bit+ bus expansion, on-chip semaphore addressing (A0–A2), interrupt mailbox addresses (3FFEh/3FFFh), and industrial-grade timing compatibility when paired with 70261S20 variants.

Technical Context

The 70261S15PF8 implements fully asynchronous dual-port architecture with independent address, control, and I/O buses per port - allowing concurrent read/write operations without external arbitration logic. Its on-chip arbitration uses BUSY flag assertion (push-pull, not open-drain) triggered by address match detection or chip-enable timing, with priority resolved via tAPS (5 ns setup) and tBDD (18 ns disable-to-valid-data) parameters.

Interrupt generation is hardware-mapped to dedicated SRAM locations (3FFEh for INTL, 3FFFh for INTR), while eight semaphore flags are accessed via SEM = VIL mode using A0–A2 as index and I/O0 as write data - all supported by full TTL-compatible signaling and automatic CE-controlled power-down (750 mW active / 5 mW standby typical).

Key Specifications

Pinout & Package

70261S15PF8 is housed in a 100-pin TQFP (Thin Quad Flatpack) package with 0.5 mm pitch, body size 14 mm × 14 mm × 1.4 mm. All VCC and GND pins must be externally decoupled per layout guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 70261S15PF8, CY7C1362AV25 trades speed and voltage compatibility for modern 3.3 V integration, while 70V27L25PF8 offers identical form factor with extended thermal reliability at the expense of 10 ns timing penalty - making it suitable for cost-sensitive industrial upgrades.

Availability

70261S15PF8 is available at Aetrix Electronics and suitable for radar signal processing, industrial PLC communication, and medical imaging controllers requiring stable component supply and long-term obsolescence management.

Supply support for 70261S15PF8 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 microcontrollers, analog, and memory solutions for automotive, industrial, and infrastructure markets.

The IDT70261 family was engineered for deterministic inter-processor communication in real-time embedded systems - delivering hardware-accelerated arbitration, interrupt, and semaphore functions in a single 5 V dual-port SRAM device.

FAQ

What is the maximum operating frequency supported by the 70261S15PF8?

The 70261S15PF8 does not operate on a clock signal - it is an asynchronous SRAM. Its maximum effective bandwidth is determined by access timing: with 15 ns read cycle time (tRC), it supports up to ~66.7 MHz sustained random access rate when interfaced with appropriately timed control logic. This enables direct connection to CPUs or FPGAs running at 50–66 MHz without wait states.

How does the BUSY arbitration logic function in the 70261S15PF8?

In the 70261S15PF8, BUSY arbitration activates when both ports attempt access to the same memory address. When M/S = H (Master), BUSYL/BUSYR are outputs that stall the lower-priority port; when M/S = L (Slave), they become inputs that inhibit writes. Priority is resolved by tAPS (5 ns setup), and tBDD (18 ns) defines the delay before valid data appears after BUSY deassertion - ensuring deterministic conflict resolution.

Can the 70261S15PF8 be used in a 32-bit data bus configuration?

Yes - the 70261S15PF8 supports 32-bit expansion via Master/Slave cascading. One device operates as Master (M/S = H) providing BUSY output, while another acts as Slave (M/S = L) accepting BUSY input. This configuration enables full-speed, error-free 32-bit word access without external logic, as confirmed in the functional description and pin configuration diagrams of the datasheet.

What are the interrupt mailbox addresses for the 70261S15PF8?

The 70261S15PF8 uses fixed SRAM addresses for interrupt signaling: writing to address 3FFFh (hex) via the left port asserts the right-port interrupt flag (INTR), and writing to 3FFEh (hex) via the right port asserts the left-port flag (INTL). These locations function as user-defined mailboxes - the 16-bit data written becomes the message payload, and reading the same address clears the respective flag.

Does the 70261S15PF8 support byte-level write operations?

Yes - the 70261S15PF8 provides separate upper-byte (UBL/UBR) and lower-byte (LBL/LBR) enable controls. When UBL = L and LBL = H, only I/O0–I/O7 are written; when UBL = H and LBL = L, only I/O8–I/O15 are written; both low enables full 16-bit writes. This feature ensures compatibility with 8-bit multiplexed buses and reduces unnecessary data corruption during partial-word updates.