CY7B951-SXI

Overview

The CY7B951 is a Local Area Network ATM Transceiver designed for SONET/SDH and ATM applications. It recovers clock and data from 51.84-MHz or 155.52-MHz NRZ/NRZI serial streams and provides differential output buffering. The device features an internal PLL that multiplies a byte-rate reference clock by eight to generate bit-rate transmit clocks. It operates on a single +5V supply with low current consumption under 65 mA. The component supports ±1% frequency agility, link status indication, and loopback testing. It is available in a 24-pin SOIC package and is compatible with fiber optic modules, coaxial cable, and twisted pair media.

Feature Summary

• Integrated clock and data recovery for high-speed serial data streams
• Internal frequency multiplier PLL for generating transmit clocks
• Differential input and output buffering for copper and optical interfaces
• Built-in link fault detection and carrier detect functionality

Applications

• SONET/SDH and ATM physical layer protocol engines
• Local Area Network (LAN) ATM transceivers
• Data mover applications operating at specified frequencies
• Interfaces with PMC-Sierra PM5345 SUNI devices

Procurement Notes

Verify the specific ordering suffix to confirm the operating temperature range and package lead composition. The 'SC' and 'SI' suffixes indicate standard tin-lead packages for commercial and industrial ranges respectively. The 'XC' and 'XI' suffixes denote Pb-Free molded SOIC packages. Ensure the selected variant matches the required thermal environment and environmental compliance standards before procurement.

Selection Notes

Select the MODE pin configuration to determine the operating frequency range. Connecting MODE to VCC selects the 155.52-MHz range requiring a 19.44-MHz reference, while connecting to ground selects the 51.84-MHz range requiring a 6.48-MHz reference. Ensure the REFCLK source accuracy meets the ±1% requirement. Consider power-down options for unused outputs to minimize total system power consumption.

Part Context

This component belongs to the Cypress Semiconductor ATM transceiver family, specifically engineered for local area network environments. It serves as a bridge between serial transmission media and parallel processing logic, handling the critical task of signal regeneration and timing recovery. The device complements other interface solutions by providing robust clock alignment and data buffering capabilities essential for high-integrity data communication.

Replacement Considerations

The datasheet notes compatibility with the PMC-Sierra PM5345 SUNI. No direct cross-model substitutes are listed in the official documentation. Verify pinout and electrical characteristics against alternative transceivers if considering a change, particularly regarding ECL/PECL voltage levels and package dimensions.