 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
IDT5V49EE501 Datasheet(PDF) 9 Page - Integrated Device Technology |
|
||||||||||||||||||||||||||||||
IDT5V49EE501 Datasheet(HTML) 9 Page - Integrated Device Technology |
|
|
9 / 33 page  IDT5V49EE501 EEPROM PROGRAMMABLE CLOCK GENERATOR CLOCK SYNTHESIZER IDT® EEPROM PROGRAMMABLE CLOCK GENERATOR 9 IDT5V49EE501 REV P 071015 Profile: Waveform starts with SS_OFFSET, SS_OFFSET + SDJ, SS_OFFSET + SDJ+1, etc. Spread Spectrum Using Sinusoidal Profile Example FIN = 25MHz, FOUT = 100MHz, Fssc = 33KHz with center spread of ±2%. Find the necessary spread spectrum register settings. Since the spread is center, the SS_OFFSET can be set to '0'. Solve for the nominal M value; keep in mind that the nominal M should be chosen to maximize the VCO. Start with D = 1, using Eq.6 and Eq.7. MNOM = 1200MHz / 25MHz = 48 Using Eq.4, we arbitrarily choose N = 22, A = 3. Now that we have the nominal M value, we can determine TSSC and NSSC by using Eq.8. Nssc * Tssc = 25MHz / (33KHz * 4) = 190 However, using Eq. 2 and Eq.3, we find that the closest value is when TSSC = 14 and NSSC = 6. Keep in mind to maximize the number of samples used to enhance the profile of the spread spectrum waveform. Tssc = 14 + 2 = 16 Nssc = 6 * 2 = 12 Nssc * Tssc = 192 Use Eq.10 to determine the value of the sigma-delta-encoded samples. ±2% = * 100)/(64 * 48) = 61.4 Either round up or down to the nearest integer value. Therefore, we end up with 61 or 62 for sigma-delta-encoded samples. Since the sigma-delta-encoded samples must not exceed 63 with SS_OFFSET set to '0', 61 or 62 is well within the limits. It is the discretion of the user to define the shape of the profile that is better suited for the intended application. Using Eq. 9 again, the actual spread for the sigma-delta-encoded samples of 56 and 57 are ±1.99% and ±2.02%, respectively. Use Eq.10 to determine if the X2 bit needs to be set; Amplitude = 48 * (1.99 or 2.02) / 100/2 = 0.48 < 1 Therefore, the X2 = '0 '. The dither bit is left to the discretion of the user. The example above was of a center spread using spread spectrum. For down spread, the nominal M value can be set one integer value lower to 47. Note that the IDT5V49EE501 should not be programmed with TSSC > '0', SS_OFFSET = '0', and SD = '0' in order to prevent an unstable state in the modulator. The PLL loop bandwidth must be at least 10x the modulation frequency along with higher damping (larger uz) to prevent the spread spectrum from being filtered and reduce extraneous noise. Refer to the LOOP FILTER section for more detail on uz. The A[3:0] must be used for spread spectrum, even if the total multiplier value is an even integer. |
Similar Part No. - IDT5V49EE501 |
|
Similar Description - IDT5V49EE501 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
