Renesas 70261S35PF

Overview

70261S35PF from IDT is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, operating at 35 ns max access time (commercial grade), supporting independent asynchronous reads/writes on left and right ports, and enabling real-time inter-processor communication in embedded control systems.

For engineers reviewing the 70261S35PF datasheet, 70261S35PF pinout, 70261S35PF application, or 70261S35PF equivalent, this device delivers deterministic port arbitration, hardware semaphore signaling, BUSY/INT flag generation, and 5V TTL-compatible operation - critical for multiprocessor memory coherency and mailbox-based messaging.

Technical Context

The 70261S35PF implements fully asynchronous dual-port architecture with separate address, control, and I/O buses per port, enabling simultaneous access to any memory location without external arbitration logic. Its on-chip arbitration resolves contention via BUSY flag assertion and supports MASTER/SLAVE cascading for 32-bit+ data width expansion.

It integrates dedicated interrupt registers at addresses 3FFE_H (left port INTR) and 3FFF_H (right port INTL), with push-pull INT/BUSY outputs and full semaphore support across eight flags addressed by A0–A2. All timing is specified under 5.0 V ±10% supply with industrial-grade variants available.

Key Specifications

Pinout & Package

70261S35PF 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 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 CY7C1362BV33-166AXC and IDT70V261S25PF, the 70261S35PF offers optimal balance of 5V compatibility, hardware mailbox semantics, and commercial-grade speed - making it ideal for cost-sensitive, mixed-voltage embedded systems requiring guaranteed inter-processor coordination.

Availability

70261S35PF is available at Aetrix Electronics and suitable for industrial PLC communication, avionics data exchange, medical imaging subsystems, and test equipment real-time buffering requiring stable component supply and long-term obsolescence management.

Supply support for 70261S35PF 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, designs high-performance memory and timing solutions for communications, computing, and industrial markets.

The IDT70261 product line delivers true dual-port SRAMs with integrated arbitration, interrupt, and semaphore logic - engineered specifically for deterministic inter-processor communication in real-time embedded systems.

FAQ

What is the maximum access time specification for the 70261S35PF?

The 70261S35PF has a maximum access time of 35 ns for commercial-grade operation (0°C to +70°C), as defined by tAA, tACE, and tABE parameters in the datasheet. This value applies under VCC = 5.0 V ±10% and specifies the worst-case delay from address/control assertion to valid data output on either port.

How does the 70261S35PF handle simultaneous access to the same memory location?

The 70261S35PF uses on-chip arbitration logic to detect address matches between ports and asserts the BUSY flag on the contending port. When M/S = H (master), BUSY is an output that stalls the slower port; when M/S = L (slave), BUSY is an input that inhibits writes. This prevents data corruption without external logic.

Can the 70261S35PF be used in a 32-bit data path configuration?

Yes - the 70261S35PF supports 32-bit expansion via MASTER/SLAVE cascading. One device is configured as master (M/S = H) providing BUSY output, while another is configured as slave (M/S = L) accepting BUSY input. This enables full-speed, error-free 32-bit word access without discrete glue logic.

What are the interrupt mailbox addresses for the 70261S35PF?

The 70261S35PF uses fixed SRAM addresses for interrupt signaling: writing to 3FFF_H on the right port asserts INTR, and writing to 3FFE_H on the left port asserts INTL. Clearing is performed by reading those same addresses. These locations remain functional as general SRAM if interrupts are unused.

Does the 70261S35PF support byte-level write control?

Yes - the 70261S35PF provides independent upper-byte (UBL/UBR) and lower-byte (LBL/LBR) enable signals. When only one byte-enable is active, only the corresponding 8-bit lane is written, preserving data in the other byte. This supports multiplexed bus protocols and partial-word updates without read-modify-write cycles.