Infineon Technologies CY7C0251-15AC

Overview

CY7C0251-15AC from Cypress Semiconductor is an 8K × 18-bit true dual-port static RAM with on-chip arbitration, semaphores, and INT/BUSY flags. It enables simultaneous asynchronous read/write access to the same memory location by independent left/right ports, supports master/slave expansion to 36+ bits, and delivers 15 ns access time at 5 V. Used in interprocessor communication buffers and dual-port video frame stores.

For engineers reviewing the CY7C0251-15AC datasheet, CY7C0251-15AC pinout, CY7C0251-15AC application, or CY7C0251-15AC equivalent, key selection criteria include dual-port arbitration behavior, semaphore latch count, BUSY flag timing (tBLA/tBLC), M/S pin configuration for width expansion, and TQFP-100 Pb-free package compatibility.

Technical Context

The CY7C0251-15AC implements fully asynchronous dual-port operation with independent CE/R/W/OE control per port and hardware-based arbitration resolving contention within tPS (≤5 ns). Its 8K × 18-bit memory array includes dedicated upper/lower byte enables (UB/ LB) and separate I/O buses (I/O0–I/O17 per port), enabling byte-selective access without external logic.

On-chip semaphores consist of eight shared latches accessed via SEM pin assertion, with A0–A2 selecting latch address and I/O0 controlling token state (0 = acquired). Interrupts use fixed mailbox addresses (1FFFH for right port, 1FFEH for left port), generating INTL/INTR pulses on cross-port writes and clearing only upon local mailbox reads.

Key Specifications

Pinout & Package

Available in 100-pin Pb-free Thin Quad Plastic Flatpack (TQFP) with 0.5 mm pitch; body size 14 mm × 14 mm, 1.4 mm height. Pin 1 marked by corner notch; thermal pad exposed on underside for enhanced heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT70V25L15PF and ISSI IS61WV102418B, the CY7C0251-15AC uniquely integrates arbitration, semaphores, and dual-mailbox interrupts in a single 100-pin package-reducing BOM count by ≥3 discrete components and eliminating timing-critical external logic design.

Availability

CY7C0251-15AC is available at Aetrix Electronics and suitable for interprocessor communication buffers, dual-port video frame stores, industrial PLC redundancy systems, and telecom line card status sharing requiring stable component supply and long-term lifecycle support.

Supply support for CY7C0251-15AC 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

Cypress Semiconductor (now part of Infineon Technologies) designs high-reliability memory and programmable solutions for industrial, automotive, and communications infrastructure.

The CY7C0251 belongs to Cypress's dual-port SRAM product line, engineered specifically for deterministic inter-processor data exchange in real-time embedded systems with strict timing and coherency requirements.

FAQ

What is the function of the M/S pin in master versus slave configuration?

In master mode (M/S = HIGH), BUSYL and BUSYR are outputs reflecting internal arbitration results; in slave mode (M/S = LOW), they become inputs accepting BUSY signals from a master device. This enables seamless 36-bit+ memory expansion using multiple CY7C0251s without external arbitration ICs or discrete logic, reducing board space and signal integrity complexity.

How do the semaphore latches prevent race conditions between ports?

Each of the eight semaphores functions as a hardware-enforced token: writing 0 to a semaphore address acquires it exclusively (the other port reads 1 until release), and writing 1 releases it. The latches guarantee atomic read-modify-write behavior with tSOP (15 ns) setup time, eliminating software-based test-and-set loops and ensuring deterministic resource ownership in hard real-time systems.

Can INTL and INTR be used simultaneously for bidirectional messaging?

Yes-INTL triggers when the right port writes to address 1FFEh, and INTR triggers when the left port writes to 1FFFh. Each mailbox is independent and self-clearing only upon local read, allowing full-duplex, low-latency inter-processor messaging with no shared memory address conflicts or software coordination overhead.

What happens if both ports attempt to access the same memory location within the tPS window?

When address match occurs within tPS ≤5 ns, on-chip arbitration asserts BUSYL or BUSYR to block the losing port's access; the winning port proceeds with deterministic timing (tACE = 15 ns). If tPS is violated, one port gains access unpredictably-so system design must ensure address setup skew remains below 5 ns to guarantee deterministic behavior.