Datenblatt-Suchmaschine für elektronische Bauteile |
|
CDC925DL Datenblatt(PDF) 4 Page - Texas Instruments |
|
CDC925DL Datenblatt(HTML) 4 Page - Texas Instruments |
4 / 18 page CDC925 133-MHz CLOCK SYNTHESIZER/DRIVER FOR PC MOTHERBOARDS WITH 3-STATE OUTPUTS SCAS633 – JULY 28, 1999 4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 spread spectrum clock (SSC) implementation for CDC925 Simultaneously switching at fixed frequency generates a significant power peak at the selected frequency, which in turn will cause EMI disturbance to the environment. The purpose of the internal frequency modulation of the CPU–PLL allows to distribute the energy to many different frequencies which reduces the power peak. A typical characteristic for a single frequency spectrum and a frequency modulated spectrum is shown in Figure 1. Highest Peak Non-SSC SSC δ of fnom fnom ∆ Figure 1. Frequency Power Spectrum With and Without the Use of SSC The modulated spectrum has its distribution left hand to the single frequency spectrum which indicates a “down-spread modulation”. The peak reduction depends on the modulation scheme and modulation profile. System performance and timing requirements are the limiting factors for actual design implementations. The implementation was driven to keep the average clock frequency closed to its upper specification limit. The modulation amount was set to approximately –0.34% (compared to – 0.5% on the CDC924). In order to allow a downstream PLL to follow the frequency modulated signal, the bandwidth of the modulation signal is limited in order to minimize SSC induced tracking skew jitter. The ideal modulation profile used for CDC925 is shown in Figure 2. 5 1015 20 25 3035 40 45 Period of Modulation Signal – µs 9.97 9.98 9.99 10 10.01 10.02 10.03 Figure 2. SSC Modulation Profile |
Ähnliche Teilenummer - CDC925DL |
|
Ähnliche Beschreibung - CDC925DL |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |