Infineon Technologies CY7C136-25NXC

Overview

CY7C136-25NXC from Cypress Semiconductor is a 2K × 8 true dual-port static RAM with independent left/right ports, 25 ns maximum access time, 5 V ±10% supply, and 52-pin PLCC package. It functions as a master dual-port memory in shared-data systems such as DSP cache or multiprocessor interconnects, enabling simultaneous read access to the same location without arbitration delay.

For engineers reviewing the CY7C136-25NXC datasheet, CY7C136-25NXC pinout, CY7C136-25NXC application, or CY7C136-25NXC equivalent, key selection criteria include BUSY flag behavior for contention resolution, INT interrupt support for port-to-port signaling, automatic per-port power-down control via CE, and compatibility with CY7C142/CY7C146 slave devices for 16-bit+ bus expansion.

Technical Context

The CY7C136-25NXC implements fully asynchronous dual-port architecture with separate address, data, and control buses for left (L) and right (R) ports. Each port features independent CE, R/W, and OE pins, enabling concurrent read/write operations across ports - subject to BUSY arbitration when accessing identical addresses.

It integrates open-drain BUSY outputs (requiring external pull-up resistors) and dedicated INT flags on both ports (7FFH/7FEH locations), supporting priority-based inter-port communication. The device uses 0.65 µm CMOS process and supports TTL/CMOS-compatible input thresholds (VIH = 2.2 V, VIL = 0.8 V).

Key Specifications

Pinout & Package

Package: 52-pin Plastic Leaded Chip Carrier (PLCC), JEDEC MS-026AC compliant, lead-free (RoHS-compliant) variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C136-25VXC, the NXC variant offers socket-mount flexibility and easier prototyping; compared with CY7C136A-25NXC, it represents the original production release with broader historical design validation - both retain identical electrical behavior and system-level timing margins.

Availability

CY7C136-25NXC is available at Aetrix Electronics and suitable for DSP cache memory, multiprocessor shared buffers, bit-slice processor interconnects, and legacy bus bridge interfaces requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for CY7C136-25NXC 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) is a U.S.-based semiconductor company specializing in memory, PSoC, and connectivity solutions for industrial, automotive, and consumer applications.

The CY7C136 belongs to Cypress's legacy dual-port SRAM product line, designed specifically for deterministic, low-latency shared-memory architectures in real-time embedded systems where software-managed arbitration is unacceptable.

FAQ

Is CY7C136-25NXC pin-compatible with CY7C136-25VXC?

Yes - both share identical electrical pinout and signal definitions across all 52 pins. The only difference is package type: NXC is 52-pin PLCC (plastic leaded chip carrier) with J-lead geometry, while VXC is 52-pin PQFP (plastic quad flat pack) with gull-wing leads. PCB layout and socket requirements differ, but schematic symbol and netlist remain interchangeable.

What is the function of the BUSY pin, and does it require external components?

BUSY is an open-drain output that goes LOW when the opposing port attempts to access the same memory address. It requires an external pull-up resistor (typically 4.7 kΩ to VCC) to assert HIGH when inactive. This signal enables hardware-level arbitration without CPU intervention, reducing latency in time-critical dual-processor systems.

Can CY7C136-25NXC operate at 3.3 V?

No - the device is specified only for 5 V ±10% (4.5 V to 5.5 V). Its internal 0.65 µm CMOS process, VIH/VIL thresholds (2.2 V/0.8 V), and DC characteristics are validated exclusively at 5 V. Operation at 3.3 V will result in undefined behavior, failed reads/writes, and potential data corruption.

How does the INT flag work, and what address triggers it?

INT is an open-drain interrupt output asserted when data is written to fixed addresses: 7FFH for the left port and 7FEH for the right port. Writing any value to those locations causes INT to go LOW (with external pull-up), signaling the other port that new data is ready. This enables lock-free, hardware-triggered inter-port communication without polling or shared registers.