Zakładka z wyszukiwarką danych komponentów |
|
ADAV801 Arkusz danych(PDF) 59 Page - Analog Devices |
|
ADAV801 Arkusz danych(HTML) 59 Page - Analog Devices |
59 / 61 page ADAV801 Rev. A | Page 58 of 60 LAYOUT CONSIDERATIONS Getting the best performance from the ADAV801 requires a careful layout of the printed circuit board (PCB). Using separate analog and digital ground planes is recommended, because these give the currents a low resistance path back to the power supplies. The ground planes should be connected in only one place, usually under the ADAV801, to prevent ground loops. The analog and digital supply pins should be decoupled to their respective ground pins with a 10 μF to 47 μF tantalum capacitor and a 0.1 μF ceramic capacitor. These capacitors should be placed as close as possible to the supply pins. ADC The ADC uses a switch capacitor input stage and is, therefore, particularly sensitive to digital noise. Sources of noise, such as PLLs or clocks, should not be routed close to the ADC section. The CAPxN and CAPxP pins form a charge reservoir for the switched capacitor section of the ADC, so keeping these nodes electrically quiet is a key factor in ensuring good performance. The capacitors connected to these pins should be of good quality, either NPO or COG, and should be placed as close as possible to CAPxN and CAPxP. DAC The DAC requires an analog filter to filter out-of-band noise from the analog output. A third-order Bessel filter is recommended, although the filter to use depends on the requirements of the application. PLL The PLL can be used to generate digital clocks, either for use internally or to clock external circuitry. Because every clock is a potential source of noise, care should be taken when using the PLL. The ADAV801’s PLL outputs can be enabled or disabled, as required. If the PLL clocks are not required by external circuitry, it is recommended that the outputs be disabled. To reduce cross-coupling between clocks, a digital ground trace can be routed on either side of the PLL clock signal, if required. The PLL has its own power supply pins. To get the best performance from the PLL and from the rest of the ADAV801, it is recommended that a separate analog supply be used. Where this is not possible, the user must decide whether to connect the PLL supply to the analog (AVDD) or digital (DVDD) supply. Connecting the PLL supply to AVDD gives the best jitter performance, but can degrade the performance of the ADC and DAC sections slightly due to the increased digital noise created on the AVDD by the PLL. Connecting the PLL supply to DVDD keeps digital noise away from the analog supply, but the jitter specifications might be reduced depending on the quality of the digital supply. Using the layout recommendations described in this section helps to reduce these effects. RESET AND POWER-DOWN CONSIDERATIONS When the ADAV801 is held in reset by bringing the RESET pin low, a number of circuit blocks remain powered up. For example, the crystal oscillator circuit based around the XIN and XOUT pins is still active, so that a stable clock source is available when the ADAV801 is taken out of reset. In addition, the VCO associated with the S/PDIF receiver is active so that the receiver locks to the incoming S/PDIF stream in the shortest possible time. Where power consumption is a concern, the individual blocks of the ADAV801 can be powered down via the control registers to gain significant power savings. Table 146 shows typical power savings when using the power-down bits in the control registers. Table 146. Typical Power Requirements Operating Mode AVDD (mA) DVDD (mA) ODVDD (mA) DIR_VDD (mA) Power (mW) Normal 50 25 5 5 280.5 Reset low 30 4 2.5 1 123.75 Power-down bits 12 0.1 1.3 0.7 46.53 |
Podobny numer części - ADAV801_17 |
|
Podobny opis - ADAV801_17 |
|
|
Link URL |
Polityka prywatności |
ALLDATASHEET.PL |
Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów 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 |