Infineon Technologies CY7B9920-5SC

Overview

CY7B9920-5SC from Cypress Semiconductor is a CMOS-output, low-skew clock buffer with integrated PLL, delivering zero input-to-output delay and <250 ps max output skew across eight outputs. It operates from 15 MHz to 80 MHz (FS pin-selectable), drives 50Ω terminated lines, and maintains 50% duty cycle - deployed in Pentium™-based computing systems for synchronized clock distribution.

For engineers reviewing the CY7B9920-5SC datasheet, CY7B9920-5SC pinout, CY7B9920-5SC application, or CY7B9920-5SC equivalent, key selection criteria include output skew tolerance (<250 ps), CMOS-level drive capability (VCC/2 thresholds), FS-selectable frequency range (15–80 MHz), and PLL lock time (≤0.5 ms) under industrial temperature conditions.

Technical Context

The CY7B9920-5SC implements a fully integrated phase-locked loop with voltage-controlled oscillator (VCO), phase/frequency detector, and filter - enabling zero-delay clock forwarding. Its three-level FS pin selects VCO operating bands (LOW/MID/HIGH), directly determining nominal output frequencies of 15–30 MHz, 25–50 MHz, or 40–80 MHz.

All eight Q[0..7] outputs are CMOS-compatible (VOH = VCC–0.75 V, VOL = 0.45 V @ IOL = 46 mA), driven from dedicated VCCN supply pins, while internal logic runs on separate VCCQ. The device supports direct REF-to-output bypass in TEST mode, decoupling the PLL for deterministic timing validation.

Key Specifications

Pinout & Package

24-pin SOIC (S13, 300-mil) package with exposed thermal pad not present; lead finish is matte tin, RoHS-compliant per legacy spec.

Key Features

Applications

Equivalent & Alternatives

CY7B9920-5SC has two verified drop-in alternatives with documented electrical and functional differences.

Compared with CY7B9920-5SI, the -5SC offers lower temperature qualification cost but reduced thermal margin; versus CY7B9920-7SC, it delivers 3× tighter skew control essential for CPU clock trees - making it the optimal choice for performance-critical computing timing.

Availability

CY7B9920-5SC is available at Aetrix Electronics and suitable for desktop motherboard design, industrial PLC backplanes, legacy embedded computing upgrades, and Pentium™-based system refurbishment requiring stable component supply over extended production lifecycles.

Supply support for CY7B9920-5SC 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 Corporation, now part of Infineon Technologies, designed high-performance timing, memory, and programmable logic devices for computing and industrial markets from 1982 until its 2020 acquisition.

CY7B9920 belongs to Cypress's low-skew clock buffer product line, engineered specifically for synchronized clock distribution in Pentium-class systems where deterministic delay and minimal inter-output skew were critical for FSB and memory interface timing.

FAQ

What is the maximum capacitive load the CY7B9920-5SC can drive per output?

The CY7B9920-5SC is characterized for 30 pF load in –2 and –5 speed grades, and 50 pF in –7 grade. Driving beyond 30 pF at 80 MHz may degrade tORISE/tOFALL and increase jitter; Cypress specifies timing only up to 30 pF for CY7B9920-5SC. External series termination remains mandatory for 50Ω line matching regardless of capacitive load.

Can the FS pin be left unconnected?

Yes - the FS pin has internal termination holding unconnected inputs at VCC/2, which corresponds to MID state (25–50 MHz range). However, Cypress warns that switching FS mid-operation may cause PLL unlock and output glitches; it must be set at power-up and held static during normal operation.

Is the CY7B9920-5SC compatible with 3.3V-only systems?

No - the device requires 5V ±10% on both VCCN and VCCQ; it does not support 3.3V core or I/O operation. Its CMOS outputs swing rail-to-rail (0.45 V to VCC–0.75 V), so interfacing with 3.3V logic requires external level translation or series resistor matching to avoid overvoltage damage.

Does the CY7B9920-5SC provide short-circuit protection on its outputs?

No - the datasheet explicitly states "CY7B9920 outputs are not short circuit protected." Absolute maximum rating for output short-circuit current is –250 mA (tested one output at a time, <1 second, <10% duty cycle), but sustained shorts will exceed thermal limits and cause permanent failure.