Renesas 70261S15PF

Overview

70261S15PF from IDT (Integrated Device Technology) 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 or DSP+FPGA co-processing architectures.

For engineers reviewing the 70261S15PF datasheet, 70261S15PF pinout, 70261S15PF application, or 70261S15PF equivalent, this page delivers verified timing parameters, master/slave cascading behavior, semaphore address mapping (A0–A2), interrupt mailbox addresses (3FFEh/3FFFh), and TQFP-100 package compatibility - all critical for lock-free shared-memory design and deterministic latency budgeting.

Technical Context

The 70261S15PF implements fully asynchronous dual-port architecture with independent control, address, and I/O buses per port. Its on-chip arbitration logic resolves contention via BUSY flag assertion (M/S = H for master output; M/S = L for slave input), and supports hardware semaphore signaling across eight flags addressed by A0–A2 using dedicated SEM pins and I/O0 write path.

Interrupt functionality is implemented via dedicated mailbox addresses: writing to 3FFFh sets INTR (right port flag), reading 3FFFh clears it; writing to 3FFEh sets INTL (left port flag), reading 3FFEh clears it. All operations require CE = VIL and SEM = VIH for RAM access, or CE = VIH and SEM = VIL for semaphore access - with strict tSWRD (5 ns) and tSPS (5 ns) timing constraints confirmed for all speed grades.

Key Specifications

Pinout & Package

70261S15PF 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 and R1EX24064ASAS, the 70261S15PF uniquely integrates interrupt mailboxes and hardware semaphores in a 5 V, 15 ns commercial-grade package - reducing BOM count and eliminating timing-critical external logic for deterministic inter-processor coordination.

Availability

70261S15PF is available at Aetrix Electronics and suitable for real-time inter-processor communication, DSP+FPGA co-processing, and industrial PLC backplane interfaces requiring stable component supply, long-term lifecycle support, and verified dual-port timing compliance.

Supply support for 70261S15PF 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, and interface solutions, later acquired by Renesas Electronics in 2019.

The 70261S15PF belongs to IDT's legacy dual-port SRAM product line, engineered specifically for deterministic, low-latency shared-memory architectures in telecommunications, industrial automation, and aerospace systems.

FAQ

What is the maximum operating frequency supported by the 70261S15PF?

The 70261S15PF does not operate on a clock signal - it is a fully asynchronous static RAM. Its performance is defined by timing parameters: tRC = 15 ns (read cycle time), enabling reliable operation with controllers generating address/control strobes at up to ~66 MHz effective rate. No internal PLL or clock multiplier is present; all timing is referenced to input signal edges per AC specifications in the datasheet.

Does the 70261S15PF support both master and slave configurations in the same system?

Yes - the 70261S15PF uses the M/S pin to configure its role: M/S = H makes BUSYL/BUSYR outputs (master mode); M/S = L makes them inputs (slave mode). In a cascaded 32-bit system, one device operates as master (driving BUSY) while others act as slaves (sampling BUSY), enabling seamless expansion without redesigning arbitration logic - as confirmed in Functional Block Diagram and Truth Table IV.

How are the interrupt mailbox addresses 3FFEh and 3FFFh implemented in the 70261S15PF memory map?

The 70261S15PF implements 3FFEh and 3FFFh as standard SRAM locations within its 16K × 16 address space. Writing to 3FFEh with CER = R/WR = VIL asserts INTL; reading 3FFEh with CEL = OEL = VIL clears it. Similarly, 3FFFh controls INTR. These addresses are not reserved or masked - they behave identically to other locations except for their interrupt-triggering function, as defined in Truth Table III and Functional Description section.

Can the 70261S15PF be used with mixed 3.3 V and 5 V logic families?

No - the 70261S15PF requires a single 5 V ±10% supply (4.5 V to 5.5 V) and is TTL-compatible. Its inputs accept VIH ≥ 2.2 V and VIL ≤ 0.8 V, but outputs swing rail-to-rail (0.4 V low, 2.4 V high @ 4 mA). Direct interface with 3.3 V logic requires level translation; the device has no dual-supply I/O or voltage-tolerant inputs - as specified in Recommended DC Operating Conditions (Table 3) and Absolute Maximum Ratings.

What is the purpose of the SEM pin, and how does it differ from CE in the 70261S15PF?

The SEM pin selects between RAM array access (SEM = VIH) and semaphore register access (SEM = VIL). When SEM = VIH and CE = VIL, the device operates as standard dual-port SRAM. When SEM = VIL and CE = VIH, the same address/data lines access eight hardware semaphore flags instead - with I/O0 controlling token state and A0–A2 selecting the flag. This dual-mode operation is exclusive and mutually protected by timing constraints (tSWRD = 5 ns), preventing accidental corruption.