Moteur de recherche de fiches techniques de composants électroniques |
|
ADN2811ACP-CML-RL Fiches technique(PDF) 10 Page - Analog Devices |
|
ADN2811ACP-CML-RL Fiches technique(HTML) 10 Page - Analog Devices |
10 / 16 page REV. A –10– ADN2811 FUNCTIONAL DESCRIPTION Clock and Data Recovery The ADN2811 will recover clock and data from serial bit streams at OC-48 as well as the 15/14 FEC rates. The data rate is selected by the RATE input (see Table I). Table I. Data Rate Selection RATE Data Rate Frequency (MHz) 0 OC-48 2488.32 1 OC-48 FEC 2666.06 Limiting Amplifier The limiting amplifier has differential inputs (PIN/NIN) that are internally terminated with 50 Ω to an on-chip voltage reference (VREF = 0.6 V typically). These inputs are normally ac-coupled, although dc-coupling is possible as long as the input common-mode voltage remains above 0.4 V (see Figures 20–22). Input offset is factory trimmed to achieve better than 4 mV typical sensitivity with minimal drift. The limiting amplifier can be driven differentially or single-ended. Slice Adjust The quantizer slicing level can be offset by ± 100 mV to mitigate the effect of ASE (amplified spontaneous emission) noise by applying a differential voltage input of ± 0.8 V to SLICEP/N inputs. If no adjustment of the slice level is needed, SLICEP/N should be tied to VCC. Loss of Signal (LOS) Detector The receiver front end level signal detect circuit indicates when the input signal level has fallen below a user adjustable threshold. The threshold is set with a single external resistor from Pin 1, THRADJ, to GND. The LOS comparator trip point versus the resistor value is illustrated in Figure 2 (this is only valid for SLICEP = SLICEN = VCC). If the input level to the ADN2811 drops below the programmed LOS threshold, SDOUT (Pin 45) will indicate the loss of signal condition with a Logic 1. The LOS response time is ~300 ns by design but will be dominated by the RC time constant in ac-coupled applications. If the LOS detector is used, the quantizer slice adjust pins must both be tied to VCC. This is to avoid interaction with the LOS threshold level. Note that it is not expected to use both LOS and slice adjust at the same time; systems with optical amplifiers need the slice adjust to evade ASE. However, a loss of signal in an optical link that uses optical amplifiers causes the optical amplifier output to be full-scale noise. Under this condition, the LOS would not detect the failure. In this case, the loss of lock signal will indi- cate the failure because the CDR circuitry will not be able to lock onto a signal that is full-scale noise. Reference Clock There are three options for providing the reference frequency to the ADN2811: differential clock, single-ended clock, or crystal oscillator. See Figures 12–14 for example configurations. The ADN2811 can accept any of the following reference clock frequencies: 19.44 MHz, 38.88 MHz, 77.76 MHz at LVTTL/ LVCMOS/LVPECL/LVDS levels or 155.52 MHz at LVPECL/ LVDS levels via the REFCLKN/P inputs, independent of data rate. The input buffer accepts any differential signal with a peak-to-peak differential amplitude of greater than 100 mV (e.g., LVPECL or LVDS) or a standard single-ended low volt- age TTL input, providing maximum system flexibility. The appropriate division ratio can be selected using the REFSEL0/1 pins, according to Table II. Phase noise and duty cycle of the reference clock are not critical and 100 ppm accuracy is sufficient. 100k 100k BUFFER ADN2811 VCC/2 REFCLKN REFCLKP CRYSTAL OSCILLATOR XO1 XO2 VCC VCC VCC REFSEL Figure 12. Differential REFCLK Configuration OUT 100k 100k BUFFER ADN2811 VCC/2 REFCLKP CRYSTAL OSCILLATOR XO1 XO2 VCC VCC VCC REFSEL CLK OSC VCC REFCLKN NC Figure 13. Single-Ended REFCLK Configuration 100k 100k BUFFER ADN2811 VCC/2 REFCLKN REFCLKP CRYSTAL OSCILLATOR XO1 XO2 REFSEL NC 19.44MHz VCC Figure 14. Crystal Oscillator Configuration |
Numéro de pièce similaire - ADN2811ACP-CML-RL |
|
Description similaire - ADN2811ACP-CML-RL |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants 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 |