Infineon Technologies CY7C197N-25PXC

Overview

CY7C197N-25PXC from Cypress Semiconductor is a 256 K × 1 CMOS static RAM organized as 262,144 words × 1 bit, featuring 25 ns access time, TTL-compatible I/O, and automatic CE-controlled power-down reducing standby current to 15 mA (CMOS inputs) or 30 mA (TTL inputs). It operates at 5 V ±10% over 0 °C to +70 °C and is used in legacy industrial controllers requiring fast, low-power, byte-wide memory expansion.

For engineers reviewing the CY7C197N-25PXC datasheet, CY7C197N-25PXC pinout, CY7C197N-25PXC application, or CY7C197N-25PXC equivalent, key selection criteria include access timing consistency under varying VCC and temperature, CE/WE dual-control write enable logic, high-impedance output behavior during deselection, and compatibility with 24-pin DIP-based PCB layouts in retrofitted embedded systems.

Technical Context

The CY7C197N-25PXC implements a 1024 × 256 memory array with separate row/column decoders and sense amplifiers. Its read cycle is initiated by CE LOW and WE HIGH, with data valid within 25 ns of address assertion (tAA) or CE assertion (tACE), and output transitions to high-impedance within 11 ns after CE or WE deassertion (tHZCE/tHZWE).

Write operation requires simultaneous CE LOW and WE LOW; the internal write duration is defined by their overlap. Power-down is fully automatic upon CE HIGH, with ISB1 = 30 mA (TTL input conditions) and ISB2 = 15 mA (CMOS input conditions), verified across full commercial temperature range.

Key Specifications

Pinout & Package

Package: 24-pin plastic Dual In-line Package (PDIP), 0.600-inch width, through-hole mount. Pin pitch: 0.100 inch. RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar static RAM applications.

Compared with AS6C4008-25ZIN and IS61LV25616AL-25TLI, the CY7C197N-25PXC uniquely supports 5 V TTL-level operation in a 24-pin DIP package with true 1-bit organization-making it irreplaceable in field-upgraded industrial hardware where mechanical form factor and voltage rail constraints are fixed.

Availability

CY7C197N-25PXC is available at Aetrix Electronics and suitable for industrial PLC data buffering, legacy microcontroller code caching, telecom line card status logging, and medical diagnostic equipment FIFO applications requiring stable component supply and long-term obsolescence management.

Supply support for CY7C197N-25PXC 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 logic solutions for industrial, automotive, and communications infrastructure markets.

The CY7C197N belongs to Cypress's legacy parallel SRAM product line, engineered specifically for 5 V embedded systems requiring pin-compatible upgrade paths from bipolar and NMOS memory technologies.

FAQ

What is the minimum required pull-up resistance on the CE pin to ensure reliable power-down behavior?

A 4.7 kΩ pull-up resistor to VCC is required on the CE pin to guarantee ISB remains within specification during VCC power-up transients. Without this, CE may float into an indeterminate state, causing ISB to exceed 30 mA and potentially violating thermal limits in enclosed enclosures.

Can CY7C197N-25PXC operate reliably at 4.5 V supply voltage?

Yes - the device is specified for 5 V ±10%, meaning 4.5 V to 5.5 V operation is fully supported. At 4.5 V, tAA increases to 28 ns (typical), and VOH drops to 2.2 V, but all parameters remain within commercial-range AC/DC specifications per Rev. *D datasheet Table 4.

Does the CY7C197N-25PXC support asynchronous write operations independent of address stability?

No - write initiation requires both CE and WE to be LOW while address lines A0–A17 are stable. The tAW (address setup to write end) parameter specifies 20 ns minimum, confirming that address validity must precede WE deassertion to avoid write corruption.

Is there a recommended decoupling capacitor value and placement for CY7C197N-25PXC in high-noise industrial environments?

A 0.1 μF X7R ceramic capacitor placed within 0.25 inch of Pin 24 (VCC) and Pin 12 (GND) is mandatory. For EMI-sensitive applications, add a 4.7 μF tantalum in parallel; layout must avoid shared traces between VCC and address/data lines to prevent coupling of switching noise into memory access timing.