Renesas 70261S20PF8

Overview

70261S20PF8 from IDT (now Renesas) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, operating at 20 ns max access time over industrial temperature range (–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 DSP co-processing, FPGA-to-processor bridging, and legacy bus arbitration systems.

For engineers reviewing the 70261S20PF8 datasheet, 70261S20PF8 pinout, 70261S20PF8 application, or 70261S20PF8 equivalent, key selection criteria include port arbitration timing (tBAA ≤ 20 ns), BUSY/INT flag behavior under contention, dual-byte enable control for multiplexed buses, and master/slave cascading capability for 32-bit+ memory expansion.

Technical Context

The 70261S20PF8 implements fully asynchronous dual-port architecture with separate address, control, and I/O buses per port. Its on-chip arbitration logic resolves simultaneous access to identical memory locations using BUSY flag assertion (M/S = H) or BUSY input synchronization (M/S = L), with tAPS = 5 ns priority setup time ensuring deterministic resolution.

It integrates full hardware semaphore signaling across eight flags (addressed via A0–A2), where writes to I/O0 update semaphore state and reads return value across all 16 I/O lines. Interrupts are triggered by writes to dedicated mailbox addresses (3FFE_H and 3FFF_H), with tINS/tINR ≤ 20 ns set/reset timing.

Key Specifications

Pinout & Package

70261S20PF8 is housed in a 100-pin TQFP (PNG100) package with 0.5 mm pitch, body size 14 mm × 14 mm × 1.4 mm. All VCC and GND pins must be connected per layout guidelines; N/C pins are internally unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C028V-20AXC and IDT70V261S20PF8, the 70261S20PF8 uniquely delivers 5V-compatible dual-port operation with built-in semaphore and interrupt hardware - reducing system-level complexity and enabling direct replacement in legacy industrial designs without voltage or logic redesign.

Availability

70261S20PF8 is available at Aetrix Electronics and suitable for industrial motor control, real-time DSP co-processing, and FPGA-based embedded systems requiring stable component supply across extended product lifecycles.

Supply support for 70261S20PF8 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, specializes in high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The 70261S20PF8 belongs to IDT's legacy dual-port SRAM family, designed specifically for deterministic, low-latency memory sharing between heterogeneous processors - targeting applications where software arbitration introduces unacceptable jitter or latency.

FAQ

What is the maximum guaranteed access time for 70261S20PF8 across its full industrial temperature range?

The 70261S20PF8 is specified for a maximum access time of 20 ns over the full industrial temperature range (–40°C to +85°C) and 5.0 V ±10% supply. This value is production-tested and guaranteed - not a typical or characterization-only figure - ensuring deterministic timing in harsh environments like factory automation or automotive under-hood modules.

How does the BUSY arbitration logic function when 70261S20PF8 is configured as a Master versus a Slave?

When M/S = H (Master), BUSYL and BUSYR are push-pull outputs that assert LOW to stall the contending port during same-address access. When M/S = L (Slave), BUSYL and BUSYR become inputs; the external master drives BUSY to inhibit writes on the slave side. The 70261S20PF8's BUSY logic enforces strict priority via tAPS = 5 ns setup time, preventing metastability.

Can 70261S20PF8 be used in a 32-bit memory system, and how is data width expansion implemented?

Yes - the 70261S20PF8 supports 32-bit+ expansion via Master/Slave cascading. One device is configured as Master (M/S = H) providing BUSY output; others as Slaves (M/S = L) accepting BUSY input. Address and control signals are shared, while I/O buses are concatenated. This eliminates external logic and maintains full 20 ns speed across the expanded width.

What are the exact memory addresses used for interrupt mailbox functionality in 70261S20PF8?

The 70261S20PF8 uses fixed addresses for interrupt signaling: writing to 3FFE_H (hex) on the right port asserts INTL on the left port; writing to 3FFF_H on the left port asserts INTR on the right port. Clearing is performed by reading those same addresses. These locations remain functional as general SRAM if interrupts are unused.

Does 70261S20PF8 support partial-word writes, and how is byte masking controlled?

Yes - 70261S20PF8 supports independent upper- and lower-byte writes via UBL/LBL (left port) and UBR/LBR (right port). 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. This enables seamless integration with 8-bit microcontrollers and multiplexed data buses without external byte-enable logic.