Renesas 70261S20PF

Overview

IDT70261S20PF from IDT (now part of Renesas) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore support, operating at 20 ns max access time in 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 and right ports - ideal for real-time inter-processor communication in embedded control systems.

For engineers reviewing the IDT70261S20PF datasheet, IDT70261S20PF pinout, IDT70261S20PF application, or IDT70261S20PF equivalent, key selection considerations include dual-port arbitration timing (tBDD ≤ 30 ns), BUSY/INT flag behavior under M/S configuration, semaphore address mapping (A0–A2), byte-selectable I/O control (UBL/LBL), and industrial-grade power-down current (ISB1 ≤ 85 mA).

Technical Context

The IDT70261S20PF implements fully asynchronous dual-port architecture with separate address, data, and control buses per port - no clock required. Its on-chip arbitration logic resolves contention via BUSY flag assertion when both ports access identical addresses, with priority determined by tAPS (5 ns setup) and M/S pin state.

It integrates full hardware semaphore signaling across eight flags (addressed by A0–A2), where writes to I/O0 toggle ownership between ports. Interrupt functionality uses dedicated mailbox addresses (3FFE_H for INTL, 3FFF_H for INTR), with interrupt set/reset timing specified as tINS/tINR ≤ 20 ns.

Key Specifications

Pinout & Package

Package: 100-pin TQFP (14 mm × 14 mm × 1.4 mm), with 25 ground pins and 12 VCC pins distributed for low-noise power delivery. Pin 1 marked via corner notch; all VCC/GND pins require local decoupling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362AV25 and R1EX24064ASAS, the IDT70261S20PF uniquely delivers 5 V-native true dual-port operation with hardware arbitration and interrupt signaling in a standard TQFP - making it irreplaceable for deterministic, low-latency shared-memory architectures requiring no external logic.

Availability

IDT70261S20PF is available at Aetrix Electronics and suitable for industrial motor drives, avionics data concentrators, and medical imaging subsystems requiring stable component supply across extended product lifecycles.

Supply support for IDT70261S20PF 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, is a fabless semiconductor company specializing in timing, memory, and interface solutions for high-performance computing and real-time systems.

The IDT70261S20PF belongs to the 70261 family of dual-port SRAMs designed specifically for deterministic inter-processor communication in industrial, aerospace, and medical equipment where hardware-enforced memory coherency is mandatory.

FAQ

What is the maximum operating frequency supported by the IDT70261S20PF?

The IDT70261S20PF has a 20 ns maximum access time, supporting up to 50 MHz sustained dual-port operation under industrial conditions. This is derived from tRC (read cycle time) ≤ 20 ns, with no minimum cycle time limitation - allowing back-to-back accesses as long as timing parameters (tAA, tACE, tAOE) are met. The IDT70261S20PF does not require a clock signal, operating fully asynchronously.

How does the BUSY arbitration logic function in the IDT70261S20PF when both ports access the same address?

When both ports assert valid addresses matching (A0L–A13L = A0R–A13R), the IDT70261S20PF's on-chip arbitration asserts BUSYL or BUSYR within tBAA ≤ 20 ns. If M/S = H (master), BUSY is an output that stalls the later-arriving port; if M/S = L (slave), BUSY is an input that inhibits writes. Priority is resolved by tAPS (5 ns setup), ensuring deterministic resolution without external logic.

Can the IDT70261S20PF be used in a 32-bit data path configuration?

Yes - the IDT70261S20PF 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 allows two 16-bit ports to operate as a coherent 32-bit interface without additional discrete logic, maintaining full-speed operation per the datasheet's "MASTER/SLAVE Dual-Port RAM approach".

What are the valid interrupt mailbox addresses for the IDT70261S20PF and how are they cleared?

The IDT70261S20PF uses address 3FFE_H to set the left-port interrupt flag (INTL) and 3FFF_H to set the right-port flag (INTR). INTL is cleared by reading 3FFE_H (CEL = OEL = VIL), and INTR is cleared by reading 3FFF_H (CER = OER = VIL). These locations are standard SRAM cells - the stored 16-bit value is user-defined data, not fixed-status bits.

Does the IDT70261S20PF support byte-level writes, and how is this controlled?

Yes - the IDT70261S20PF supports independent upper- and lower-byte writes via UBL/LBL pins. When UBL = L and LBL = H, only I/O8–I/O15 (upper byte) are written; when UBL = H and LBL = L, only I/O0–I/O7 (lower byte) are written; both low enables full 16-bit write. This is essential for interfacing with 8-bit peripherals or handling misaligned data in mixed-width systems.