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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Renesas 70261S25PF8

Name: 70261S25PF8
Brand: Renesas
SKU: 70261S25PF8
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 70261S25PF8

Manufacturer:: Renesas

Category:: Memory

Package:: 100-LQFP

Datasheet:: 70261S25PF8.pdf

Description:: IC SRAM 256KBIT PARALLEL 100TQFP

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Product details

Overview

70261S25PF8 from IDT (now Renesas) is a high-speed 16K × 16 true dual-port static RAM with interrupt and semaphore logic, operating at 25 ns max access time (commercial/industrial), supporting independent asynchronous reads/writes on left and right ports, and used in real-time inter-processor communication systems such as radar signal processors and industrial PLC backplanes.

For engineers reviewing the 70261S25PF8 datasheet, 70261S25PF8 pinout, 70261S25PF8 application, or 70261S25PF8 equivalent, key selection considerations include port arbitration timing (tBDD ≤ 30 ns), interrupt flag behavior (INTL/INTR set/clear via dedicated addresses 3FFE/3FFF), dual-byte control (UBL/LBL), and 100-pin TQFP packaging with 5 V ±10% supply compatibility.

Technical Context

The 70261S25PF8 implements full hardware port arbitration using push-pull BUSY signaling (not open-drain), with master/slave configuration via M/S pin to enable cascaded 32-bit+ memory expansion. Its on-chip semaphore logic supports eight shared flags addressed by A0–A2, accessed only when CE = VIH and SEM = VIL.

It features separate upper- and lower-byte enables (UBL/LBL), independent chip enables per port (CEL/CER), and fully asynchronous operation - no clock required. The device uses CMOS technology, draws 170 mA typical dynamic current (both ports active), and enters low-power standby (≤25 mA ISB1) when CE is deasserted.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	16,384 × 16 bits (256 KB total); supports simultaneous read/write to same address with BUSY arbitration
Access Time	25 ns max (tAA, tACE, tABE); ensures sub-40 MHz sustained dual-port throughput in real-time control loops
Supply Voltage	5.0 V ±10% (4.5–5.5 V); TTL-compatible interface eliminates level-shifting in legacy 5 V systems
Operating Temp	−40°C to +85°C (industrial grade); validated for use in motor drives and outdoor telecom equipment
Power Dissipation	Active: 750 mW typ.; Standby: 5 mW typ. (IDT70261S variant); enables thermal management in dense FPGA co-processor modules
Interrupt Logic	Dedicated mailbox addresses 3FFE_H (INTL) and 3FFF_H (INTR); enables lock-free inter-core messaging without software polling
Semaphore Count	8 hardware flags, addressed by A0–A2; allows fine-grained resource locking across two independent processor domains

Pinout & Package

70261S25PF8 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 individually decoupled per layout guidelines.

Pin/Terminal	Circuit Role	Design Meaning
CEL / CER	Left/Right Chip Enable	Independent port activation; each port enters full standby (ISB3 ≤ 1.0 mA) when its CE = VIH
R/WL / R/WR	Left/Right Read/Write Control	Active-low write strobe; controls data direction on I/O0–I/O15 without requiring external direction logic
OEL / OER	Left/Right Output Enable	Tri-states I/O bus independently per port; enables mixed read/write concurrency (e.g., read port A while writing port B)
UBL / UBR, LBL / LBR	Upper/Lower Byte Select	Enables byte-level writes to 16-bit bus; critical for partial-word updates in protocol stack buffers
INTL / INTR	Left/Right Interrupt Flag Output	Open-collector compatible (per datasheet note: non-tri-stated push-pull); asserts on write to 3FFE_H/3FFF_H mailbox
BUSYL / BUSYR	Left/Right Busy Flag	Push-pull output (MASTER) or input (SLAVE); blocks conflicting writes during address contention; tBDD ≤ 30 ns guarantees deterministic resolution
M/S	Master/Slave Select	Configures BUSY pin function: HIGH = BUSY output (master), LOW = BUSY input (slave); enables daisy-chained arbitration in multi-device systems
A0L–A13L / A0R–A13R	Left/Right Address Inputs	14-bit addressing per port (16K depth); no internal address latching - fully combinatorial access path
I/O0L–I/O15L / I/O0R–I/O15R	Left/Right Data I/O	Bidirectional 16-bit buses; support simultaneous 32-bit word access when cascaded as MASTER/SLAVE pair

Key Features

Feature	Design Value
True Dual-Port Architecture	Enables zero-wait-state concurrent access from two independent processors or DMA engines without external arbitration logic
Hardware Semaphore Logic	Eight dedicated flags accessible via A0–A2; eliminates software mutex overhead in real-time OS environments
Interrupt Mailbox Addresses	Fixed locations 3FFE_H (left INTL) and 3FFF_H (right INTR); provide atomic message-passing without polling or timer interrupts
Master/Slave Cascading	Supports 32-bit+ data bus expansion using M/S pin and BUSY chaining; maintains full speed without glue logic
Low-Power Standby Mode	ISB3 ≤ 1.0 mA (full standby, CMOS inputs); extends uptime in battery-backed industrial controllers

Applications

Radar Signal Processor	Industrial PLC Backplane
Use Scenario: Two DSP cores exchange FFT results and control parameters in real time during pulse-Doppler processing. IC Role / Device Role / Timing Role: 70261S25PF8 serves as shared memory buffer with hardware arbitration, enabling deterministic latency <30 ns between write commit and BUSY assertion. Use Value: Eliminates software semaphore polling, reducing CPU load by >12% and guaranteeing worst-case inter-core latency under 45 ns.	Use Scenario: PLC main CPU and motion control coprocessor coordinate axis synchronization and I/O state updates over a common memory space. IC Role / Device Role / Timing Role: 70261S25PF8 acts as dual-access register bank, with INTL/INTR flags triggering event-driven task scheduling. Use Value: Enables sub-millisecond response to encoder interrupts and eliminates race conditions during cyclic I/O scan updates.
Avionics Flight Computer	Medical Imaging Controller
Use Scenario: Safety-critical flight management unit and redundant monitoring processor share sensor fusion data and health status registers. IC Role / Device Role / Timing Role: 70261S25PF8 provides fault-tolerant shared memory with BUSY-controlled write inhibition and semaphore-protected configuration registers. Use Value: Ensures atomic updates to navigation constants and satisfies DO-254 Level A determinism requirements for concurrent access.	Use Scenario: MRI subsystem controller transfers raw k-space data from ADC array to reconstruction engine while managing DMA descriptors. IC Role / Device Role / Timing Role: 70261S25PF8 functions as high-bandwidth frame buffer with separate read/write ports, synchronized via BUSY handshake. Use Value: Sustains 1.2 GB/s effective bandwidth (dual 16-bit ports @ 25 ns cycle), eliminating PCIe bottlenecks in real-time image reconstruction.

Radar Signal Processor

Industrial PLC Backplane

Use Scenario: Two DSP cores exchange FFT results and control parameters in real time during pulse-Doppler processing.

IC Role / Device Role / Timing Role: 70261S25PF8 serves as shared memory buffer with hardware arbitration, enabling deterministic latency <30 ns between write commit and BUSY assertion.

Use Value: Eliminates software semaphore polling, reducing CPU load by >12% and guaranteeing worst-case inter-core latency under 45 ns.

Use Scenario: PLC main CPU and motion control coprocessor coordinate axis synchronization and I/O state updates over a common memory space.

IC Role / Device Role / Timing Role: 70261S25PF8 acts as dual-access register bank, with INTL/INTR flags triggering event-driven task scheduling.

Use Value: Enables sub-millisecond response to encoder interrupts and eliminates race conditions during cyclic I/O scan updates.

Avionics Flight Computer

Medical Imaging Controller

Use Scenario: Safety-critical flight management unit and redundant monitoring processor share sensor fusion data and health status registers.

IC Role / Device Role / Timing Role: 70261S25PF8 provides fault-tolerant shared memory with BUSY-controlled write inhibition and semaphore-protected configuration registers.

Use Value: Ensures atomic updates to navigation constants and satisfies DO-254 Level A determinism requirements for concurrent access.

Use Scenario: MRI subsystem controller transfers raw k-space data from ADC array to reconstruction engine while managing DMA descriptors.

IC Role / Device Role / Timing Role: 70261S25PF8 functions as high-bandwidth frame buffer with separate read/write ports, synchronized via BUSY handshake.

Use Value: Sustains 1.2 GB/s effective bandwidth (dual 16-bit ports @ 25 ns cycle), eliminating PCIe bottlenecks in real-time image reconstruction.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
CY7C1362BV33-25ZXI	3.3 V core supply; 25 ns access; 16K × 16; no built-in interrupt/mailbox logic	Requires external logic for interrupt generation; suited for 3.3 V systems where voltage translation is undesirable	Select when migrating to lower-voltage platforms and interrupt functionality is implemented in FPGA or MCU firmware
AS7C316000B-25JCIN	5 V supply; 25 ns access; 16K × 16; no BUSY arbitration or semaphore logic; no interrupt flags	Lacks hardware arbitration - requires external priority encoder or software coordination for concurrent access	Select for cost-sensitive applications where dual-port concurrency is infrequent and deterministic latency is not required

Compared with CY7C1362BV33-25ZXI and AS7C316000B-25JCIN, the 70261S25PF8 uniquely integrates interrupt mailboxes, push-pull BUSY arbitration, and eight semaphores - reducing BOM count by ≥3 discrete components and guaranteeing sub-45 ns worst-case inter-port conflict resolution.

Availability

70261S25PF8 is available at Aetrix Electronics and suitable for radar signal processors, industrial PLC backplanes, avionics flight computers, and medical imaging controllers requiring stable component supply across extended product lifecycles.

Supply support for 70261S25PF8 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 high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The IDT70261 family was designed specifically for deterministic, low-latency inter-processor communication in real-time embedded systems - emphasizing hardware arbitration, interrupt offload, and seamless 32-bit bus expansion without external logic.

FAQ

What is the maximum guaranteed access time for the 70261S25PF8?

The 70261S25PF8 has a maximum access time of 25 ns for address access (tAA), chip enable access (tACE), and byte enable access (tABE), specified across both commercial (0°C to +70°C) and industrial (−40°C to +85°C) temperature ranges. This ensures deterministic timing in hard real-time systems where jitter must remain below 5 ns.

How does the BUSY arbitration logic work in the 70261S25PF8?

The 70261S25PF8 uses push-pull BUSY outputs (BUSYL/BUSYR) that assert when both ports attempt simultaneous access to the same memory location. When configured as MASTER (M/S = H), BUSY signals block the later-arriving write; as SLAVE (M/S = L), BUSY is an input that inhibits local writes. tBDD ≤ 30 ns guarantees valid data after BUSY deassertion.

Can the 70261S25PF8 be used in a 32-bit data bus configuration?

Yes - the 70261S25PF8 supports 32-bit expansion via MASTER/SLAVE cascading. One device is configured as MASTER (M/S = H) and another as SLAVE (M/S = L), with BUSY chaining and shared address/data routing. This preserves full 25 ns access speed without adding wait states or external glue logic.

What are the interrupt mailbox addresses for the 70261S25PF8?

The 70261S25PF8 uses fixed interrupt mailbox addresses: writing to address 3FFE_H sets the left-port interrupt flag (INTL), and writing to 3FFF_H sets the right-port flag (INTR). Clearing is performed by reading those same addresses. These locations are reserved for interrupt use only when the feature is enabled.

Does the 70261S25PF8 support byte-selectable writes?

Yes - the 70261S25PF8 provides independent upper-byte (UBL/UBR) and lower-byte (LBL/LBR) enables, allowing 8-bit writes to either half of the 16-bit data bus. This is essential for protocol stack buffers and partial register updates without read-modify-write cycles.

70261S25PF8 Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: -

Package/Case:: 100-LQFP

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

Memory Type:: Volatile

Memory Format:: SRAM

Technology:: SRAM - Dual Port, Asynchronous

Memory Size:: 256Kbit

Memory Organization:: 16K x 16

Memory Interface:: Parallel

Clock Frequency:: -

Write Cycle Time - Word, Page:: 25ns

Access Time:: 25 ns

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 100-TQFP (14x14)

70261S25PF8 FAQ

1.How can I place an order for 70261S25PF8 through Aetrix?

Please submit a Request for Quotation (RFQ) for 70261S25PF8 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 70261S25PF8 reliable?

The price and inventory of 70261S25PF8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 70261S25PF8 is usually 5 days.

3.What payment methods are accepted for 70261S25PF8?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 70261S25PF8 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 70261S25PF8?

70261S25PF8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 70261S25PF8 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 70261S25PF8?

For technical support, including 70261S25PF8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 70261S25PF8 requirements.

6.How does Aetrix verify that 70261S25PF8 is sourced from the original manufacturer or authorized distributors?

All 70261S25PF8 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 70261S25PF8 meets industry standards.

7.What is the process for return or replacement of 70261S25PF8?

All 70261S25PF8 units undergo pre-shipment inspection (PSI). If there is an issue with 70261S25PF8, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 70261S25PF8 part is unused and in its original packaging.

Return procedure for 70261S25PF8:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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