Renesas 70261L35PFI

Overview

IDT70261L35PFI from IDT (now Renesas) is a high-speed 16K × 16 dual-port static RAM with interrupt and semaphore support, designed for real-time inter-processor communication in embedded systems. It features 35 ns max read cycle time, 5 V ±10% single-supply operation, industrial temperature range (−40°C to +85°C), and 100-pin TQFP packaging. Used in telecom line cards, motor control co-processors, and FPGA-based data acquisition where deterministic port arbitration is required.

For engineers reviewing the IDT70261L35PFI datasheet, IDT70261L35PFI pinout, IDT70261L35PFI application, or IDT70261L35PFI equivalent, key selection criteria include BUSY/INT flag timing (tINS ≤ 25 ns), dual-port arbitration latency (tBDD ≤ 35 ns), low-power standby current (ISB3 = 0.2 mA typ.), and TTL-compatible I/O with separate upper/lower byte enables for multiplexed bus interfacing.

Technical Context

The IDT70261L35PFI implements fully asynchronous dual-port architecture with independent left/right address, control, and 16-bit bidirectional I/O buses. Each port has dedicated CE, R/W, OE, UB/LB, and SEM controls enabling concurrent read/write access to any memory location - including simultaneous access to the same address, resolved via hardware BUSY arbitration.

It integrates on-chip semaphore logic (8 flags addressed by A0–A2), interrupt generation via mailbox addresses (3FFEh/3FFFh), and Master/Slave cascading capability using M/S pin for 32-bit+ word expansion. The device uses CMOS process with automatic power-down per port when CE = VIH, achieving ISB3 = 0.2 mA typical full-standby current.

Key Specifications

Pinout & Package

Package: 100-pin Thin Quad Flatpack (TQFP), 14 mm × 14 mm × 1.4 mm body, lead pitch 0.5 mm. All VCC (pins 12, 24, 36, 48, 60, 72, 84, 96) and GND (pins 13, 25, 37, 49, 61, 73, 85, 97) pins must be decoupled locally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C028V-35AC, IDT70261L35PFI delivers integrated semaphore and interrupt functions that reduce software overhead and improve determinism; compared with R1EX24064ASAS0I#U0, it provides true parallel dual-port bandwidth and hardware arbitration essential for real-time inter-processor communication.

Availability

IDT70261L35PFI is available at Aetrix Electronics and suitable for telecom infrastructure, industrial motor control, and automotive ADAS applications requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.

Supply support for IDT70261L35PFI 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 acquired Integrated Device Technology (IDT) in 2019, inheriting its high-performance memory and timing portfolio. IDT was known for innovation in dual-port SRAM, clock generation, and RF solutions.

IDT70261L35PFI belongs to IDT's legacy high-speed dual-port SRAM family, engineered specifically for deterministic inter-processor communication in real-time embedded systems where hardware arbitration and low-latency signaling are mandatory.

FAQ

What is the maximum operating frequency supported by the IDT70261L35PFI?

The IDT70261L35PFI supports a maximum read cycle time (tRC) of 35 ns, corresponding to a theoretical maximum sustained read frequency of 28.6 MHz. This assumes ideal signal integrity and proper decoupling; actual system clocking depends on address setup/hold times (tAS = 0 ns min) and output enable timing (tAOE ≤ 20 ns).

How does the BUSY arbitration logic work in the IDT70261L35PFI?

In IDT70261L35PFI, BUSY arbitration resolves simultaneous access to the same memory address: when M/S = H (Master), BUSYL/BUSYR assert as outputs to stall the later-arriving port; when M/S = L (Slave), BUSYL/BUSYR serve as inputs that inhibit writes. Timing parameters tBAA (≤20 ns) and tBDD (≤35 ns) define response latency and data validity window.

Can the IDT70261L35PFI operate with only one port active?

Yes - IDT70261L35PFI supports asymmetric operation. With CEL = VIH and CER = VIL, only the right port is active; ISB4 current is 90 mA typical (commercial) or 110 mA typical (industrial). Full standby (ISB3 = 0.2 mA) occurs when both CE pins are high and all inputs are CMOS-level.

What are the valid interrupt mailbox addresses for the IDT70261L35PFI?

The IDT70261L35PFI uses fixed SRAM addresses for interrupt signaling: writing to 3FFEh (hex) on the right port asserts INTL; writing to 3FFFh (hex) on the left port asserts INTR. Clearing is performed by reading the same address - e.g., reading 3FFFh clears INTR. These locations remain usable as general memory if interrupts are disabled.

Is the IDT70261L35PFI pin-compatible with other speed grades in the IDT70261 family?

Yes - all IDT70261 variants (e.g., IDT70261L20PFI, IDT70261L25PFI) share identical 100-pin TQFP packaging and pinout. Speed grade differences (15/20/25/35/55 ns) affect internal timing only; no PCB redesign is needed when upgrading within the same L/S suffix and temperature grade.