Renesas 70V261S55PF

Overview

70V261S55PF from IDT is a high-speed 3.3V 16K × 16 true dual-port static RAM with independent left/right ports, 55 ns max access time (commercial grade), integrated semaphore logic, and interrupt flag support - used in real-time interprocessor communication systems requiring concurrent memory access without arbitration overhead.

For engineers reviewing the 70V261S55PF datasheet, 70V261S55PF pinout, 70V261S55PF application, or 70V261S55PF equivalent, this device delivers deterministic port-to-port contention resolution via hardware BUSY arbitration, byte-selectable I/O control, and master/slave cascading for 32-bit+ data width expansion in telecom line cards and industrial motion controllers.

Technical Context

The 70V261S55PF implements fully asynchronous dual-port architecture with separate address, control, and bidirectional I/O buses per port. It integrates on-chip arbitration logic that asserts BUSY outputs based on chip enable and address match timing - not R/W state - enabling deterministic conflict resolution between ports.

It supports two distinct operational modes: MASTER (M/S = VIH) where BUSYL/BUSYR are push-pull outputs indicating port contention, and SLAVE (M/S = VIL) where BUSY pins become write-inhibit inputs. Semaphore access uses dedicated CE/SEM polarity inversion (CE = VIH, SEM = VIL) to isolate eight 1-bit flags addressed by A0–A2.

Key Specifications

Pinout & Package

70V261S55PF is housed in a 100-pin Thin Quad Flatpack (TQFP) with 0.5 mm pitch, 14 mm × 14 mm body, and exposed thermal pad (not electrically connected). All VCC and GND pins must be decoupled per layout guidelines; pin 1 marked by corner cut or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV33-55AXI and IDT70V25L15PF8, the 70V261S55PF uniquely balances commercial-speed performance, hardware arbitration, and drop-in replaceability in legacy IDT-based designs - making it optimal for cost-constrained, timing-deterministic interprocessor communication where semaphores and interrupts are mandatory.

Availability

70V261S55PF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial motion control, avionics display systems, and medical imaging equipment requiring stable component supply and long-term obsolescence management.

Supply support for 70V261S55PF 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) is a fabless semiconductor company specializing in high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The 70V261S55PF belongs to IDT's high-speed dual-port SRAM product line, designed specifically for deterministic interprocessor communication in real-time embedded systems where concurrent memory access and hardware arbitration are essential.

FAQ

What is the maximum operating frequency supported by the 70V261S55PF?

The 70V261S55PF does not operate on a clock signal - it is a fully asynchronous static RAM. Its timing is defined by access parameters: tRC = 55 ns (read cycle time), tWC = 55 ns (write cycle time), and tAA = 55 ns (address access time) under commercial conditions (0°C to +70°C, VCC = 3.3 V ±0.3 V). These values set the upper bound for sustained random access rates, corresponding to ~18.2 MHz effective throughput in best-case sequential operation.

How does the BUSY arbitration logic function in the 70V261S55PF when configured as a master?

When M/S = VIH (master mode), the 70V261S55PF asserts BUSYL or BUSYR as push-pull outputs if the opposite port accesses the same address during its own CE-active window. The arbitration is based solely on chip enable and address match - not R/W state - and resolves contention within 45 ns (tBAA max). This signal can stall the contending port externally or trigger an interrupt, ensuring deterministic data integrity without software intervention.

Can the 70V261S55PF be used in a slave-only configuration without a master device?

Yes - the 70V261S55PF operates correctly as a standalone slave (M/S = VIL) with BUSYL/BUSYR configured as write-inhibit inputs. In this mode, external logic must drive BUSY signals low to block writes, or tie them high for normal operation. No master device is required unless width expansion or automatic BUSY generation is needed. All memory, semaphore, and interrupt functions remain fully operational.

What are the voltage thresholds for VIH and VIL on control inputs of the 70V261S55PF?

Per the datasheet, VIH (input high voltage) is guaranteed ≥2.2 V and ≤VCC + 0.3 V; VIL (input low voltage) is guaranteed ≤0.8 V and ≥−0.3 V (for pulse width <10 ns). At VCC = 3.3 V, this yields noise margins of 1.1 V (high) and 0.8 V (low), ensuring robust TTL-level compatibility without external level shifters in standard 3.3 V systems.

How are the interrupt flags INTL and INTR triggered and cleared in the 70V261S55PF?

INTL is asserted when the right port writes to address 0x3FFE (CER = R/WR = VIL); INTR is asserted when the left port writes to 0x3FFF. To clear INTL, the left port reads 0x3FFE (CEL = OEL = VIL); to clear INTR, the right port reads 0x3FFF (CER = OER = VIL). Both flags are push-pull outputs with VOH ≥2.4 V and VOL ≤0.4 V at ±4 mA load - directly interfaceable with 3.3 V logic inputs.