Infineon Technologies CYDC128B08-55AXI

Overview

CYDC128B08-55AXI from Cypress Semiconductor is a 128K × 8-bit true dual-port static RAM with independent 1.8V/2.5V/3.0V I/Os per port, 55 ns maximum access time, 15 mA typical active current at 1.8V, and 2 µA typical ISB3 standby current. It enables simultaneous asynchronous read/write access to shared memory in interprocessor communication systems, supporting master/slave expansion to 32-bit data width via M/S pin and on-chip arbitration.

For engineers reviewing the CYDC128B08-55AXI datasheet, CYDC128B08-55AXI pinout, CYDC128B08-55AXI application, or CYDC128B08-55AXI equivalent, key selection criteria include port-independent I/O voltage support, BUSY/INT flag timing for contention resolution, semaphore latch behavior, and TQFP-100 package compatibility with industrial temperature range (–40°C to +85°C).

Technical Context

This device implements fully asynchronous dual-port SRAM architecture with separate address, data, and control buses for left and right ports. It integrates on-chip arbitration logic that resolves simultaneous access to the same memory location using BUSY assertion with tBLA/tBLC timing, and supports mailbox-based port-to-port interrupt signaling via dedicated high-address locations (1FFEh/1FFFh).

The CYDC128B08-55AXI includes eight shared semaphore latches accessed via SEM pin, where write-zero grants exclusive resource ownership and read-back confirms acquisition; it also provides open-drain Output Drive Registers (ODR0–ODR4) at address x0001 and Input Read Registers (IRR0/IRR1) at x0000 - though IRR is disabled in this variant as A13L/A13R are used for addressing.

Key Specifications

Pinout & Package

Package: 100-pin TQFP (14 mm × 14 mm × 1.4 mm), lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT70V27L15PF8 and IS61WV1288EBLL-15NLI, CYDC128B08-55AXI uniquely delivers port-isolated I/O, integrated arbitration, and hardware semaphores in a single 100-pin TQFP - reducing BOM count and eliminating timing-critical external logic for industrial multiprocessor systems.

Availability

CYDC128B08-55AXI is available at Aetrix Electronics and suitable for industrial PLC communication buffers, medical imaging frame buffers, avionics data loggers, and automated test equipment pattern memory requiring stable component supply and long-term lifecycle assurance.

Supply support for CYDC128B08-55AXI 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.

CYDC dual-port SRAM product line targets deterministic interprocessor communication in real-time embedded systems, emphasizing low-power operation, mixed-voltage interoperability, and hardware-accelerated resource sharing.

FAQ

What is the function of the M/S pin in CYDC128B08-55AXI?

The M/S pin configures the device as master (HIGH) or slave (LOW) for 32-bit data bus expansion. In master mode, BUSYR becomes an output signaling arbitration result to downstream slaves; in slave mode, BUSYL serves as input to synchronize write timing. This eliminates external logic for width expansion.

How does the semaphore logic prevent resource conflicts between ports?

Eight dedicated semaphore latches operate independently of main memory. Writing '0' to a semaphore address claims ownership; reading back '0' confirms success. The latch remains locked to the winning port until it writes '1'. This hardware-enforced mutual exclusion avoids software race conditions in shared peripheral access.

Can CYDC128B08-55AXI operate with different I/O voltages on left and right ports?

Yes - VDDIOL and VDDIOR are separate pins enabling independent I/O voltage assignment. Supported standards include 1.8V/2.5V LVCMOS and 3.0V LVTTL, provided each VDDIO ≥ VCC. This allows direct interfacing with heterogeneous processors (e.g., 1.8V FPGA and 3.0V microcontroller) without level shifters.

Why is the Input Read Register (IRR) not functional in CYDC128B08-55AXI?

In CYDC128B08 variants, pins IRR0 and IRR1 are repurposed as A13L and A13R address lines to support the full 128K × 8-bit (13-bit) addressing range. This trade-off disables the IRR feature but enables maximum memory depth - confirmed in datasheet notes 8–10 and pin configuration diagrams.