Infineon Technologies CY7B9920-5SI

Overview

CY7B9920-5SI 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 15–80 MHz (FS-selectable), drives 50Ω terminated lines, and maintains 50% duty cycle - used in Pentium™-based computer systems for synchronized clock distribution to memory controllers and I/O peripherals.

For engineers reviewing the CY7B9920-5SI datasheet, CY7B9920-5SI pinout, CY7B9920-5SI application, or CY7B9920-5SI equivalent, key selection criteria include output skew tolerance (<250 ps), industrial temperature support (–40°C to +85°C), CMOS output drive capability, FS-controlled frequency range selection, and PLL lock time (≤0.5 ms).

Technical Context

The CY7B9920-5SI 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 (15–30 MHz, 25–50 MHz, or 40–80 MHz), while the FB input accepts feedback from any Qx output to close the loop.

All eight CMOS outputs (Q0–Q7) are independently buffered, each capable of driving 50Ω transmission lines terminated at VCC/2. The device uses dual supplies: VCCQ powers internal logic and PLL circuitry, while VCCN powers output drivers - supporting independent noise isolation and current optimization per output pair.

Key Specifications

Pinout & Package

Package: 24-pin SOIC (S13, 300-mil width), surface-mount, RoHS-compliant leadframe.

Key Features

Applications

Equivalent & Alternatives

CY7B9920-5SI has documented drop-in alternatives with verified functional overlap in industrial clock buffering applications.

Compared with IDT5V985-5JGI and ICS552MI-01LFT, CY7B9920-5SI uniquely combines industrial temperature rating, CMOS 5V drive, integrated PLL for zero-delay operation, and 24-pin SOIC compatibility - making it the sole option for legacy Pentium™-class systems requiring precise, scalable, and robust clock distribution.

Availability

CY7B9920-5SI is available at Aetrix Electronics and suitable for desktop motherboard design, industrial PLC timing, telecom line card synchronization, and Pentium™-based workstation development requiring stable component supply across extended temperature ranges.

Supply support for CY7B9920-5SI 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 solutions 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 high-speed computer systems requiring deterministic, jitter-controlled clock distribution with minimal board-level timing margin loss.

FAQ

What is the function of the FS pin on CY7B9920-5SI?

The FS (Frequency Select) pin is a three-level input that configures the VCO's operating frequency band: LOW enables 15–30 MHz, MID enables 25–50 MHz, and HIGH enables 40–80 MHz. It directly sets the VCO gain and tuning range - incorrect FS setting causes failure to lock or excessive jitter. Internal termination holds unconnected FS at VCC/2, but stable operation requires explicit connection to VCC, GND, or a defined mid-voltage.

Can CY7B9920-5SI drive unterminated loads?

No - CY7B9920-5SI is specified only for 50Ω-terminated transmission lines referenced to VCC/2. Driving unterminated or high-impedance loads causes signal reflections, degraded edge fidelity, and increased jitter (>200 ps RMS). The output stage is optimized for controlled-impedance routing; use series termination or proper PCB stackup to maintain 50Ω characteristic impedance from driver to receiver.

How does the TEST pin affect PLL operation?

When TEST is grounded (LOW), the device operates in normal PLL mode with zero-delay feedback. When pulled to MID or HIGH, the internal PLL disconnects and REF passes directly to all Qx outputs - bypassing phase alignment. This mode is for functional validation only; timing parameters (skew, jitter, duty cycle) are not guaranteed, and tLOCK does not apply.

Is CY7B9920-5SI pin-compatible with CY7B9910-5SI?

Yes - both share identical 24-pin SOIC (S13) pinout, power sequencing, and control interface. The only difference is output logic family: CY7B9920-5SI delivers CMOS levels (VCC-referenced), while CY7B9910-5SI delivers TTL levels (2.06V threshold). Swapping requires verifying receiver input thresholds and adjusting termination voltage accordingly.