Programmable clock generators aid EMI control

The CY25100SC and CY25100ZC are the industry's first field programmable spread spectrum clock generators.

The CY25100SC and CY25100ZC are the industry's first field programmable spread spectrum clock generators (SSCGs).

In an effort to provide a complete SSCG solution, Cypress has also released a programming kit (CY3672-PRG) as well as a socket adapter (CY3690/91) to accompany the new devices.

The SSCG and programming kit combination enables versatile programming whereby a single device can replace hundreds of fixed-function SSCGs.

Clocks used in digital systems, such as laser and ink jet printers, LCD panels, and personal computers, are one of the primary sources of unwanted electromagnetic interference (EMI).

Energy peaks, resulting from increasing frequencies and faster edge rates, become the source of EMI.

Spread spectrum clock generators reduce the peak energy by slowly modulating the clock frequency.

Cypress is the only company to offer field-programmable SSCGs, enabling the designer to adjust the programmable input clock frequencies and modulation amount (spread percent) to reduce EMI levels with ease.

The programmable spread spectrum EMI reduction capability and other timing functions including frequency synthesis are integrated into the CY25100SC and CY25100ZC, significantly enhancing system performance by eliminating the need for expensive crystal oscillators, thereby reducing system cost while reducing EMI levels.

"It's not a question of whether or not your system has EMI, it's a matter of how much EMI you have and how you are going to minimise it", said Cavit Ozdalga, Marketing Manager for Cypress's Timing Technology Division.

"By using programmable spread spectrum technology over alternative solutions such as shielding or filtering, Cypress provides the maximum amount of EMI reduction across the entire system.

Even more importantly, Cypress enables designers to program the device so that they can chose exactly how much EMI reduction is required to optimise their system during the electromagnetic compliance tests thereby eliminating the need for expensive and time consuming redesign cycles".

The CY25100 offers a wide operating output frequency range, which enables designers to program the EMI reduction from 3 to 200MHz.

In order to meet regulatory agency electromagnetic compliance requirements, programmable spread spectrum feature provide a wide range of down or centre spread percentages (0.5 to 5.0%) for maximum EMI reduction.

Depending on the application, the CY25100 provides up to 20dB EMI reduction using a worst case harmonic.

The CY3672 programming kit enables any user with a personal computer (PC) the ability to program the CY25100 quickly and easily.

The only two setup requirements are a power connection and a parallel port connection with the PC.

The CY3672 offers quick and easy prototyping using a Microsoft Windows 95, 98, NT, 2K, Me and XP compatible interface.

The CY3690/91 socket adapter rounds out the complete SSCG solution providing designers with the ability to program the chip right at their desktop.

Samples of both the CY25100ZC and CY25100SC are available now.

The CY25100ZC is available in a space saving 8-pin TSSOP package.

The CY25100SC is available in an 8-pin SOIC package.

Prices range from $1.75 to $1.55 per unit in 1000-unit quantities.

The CY3672-PRG programming kit is available now for $200.00.

The CY3690 and CY3691 socket adapter kits for TSSOP and SOIC packages are available today for $70.00 each.

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