Moteur de recherche de fiches techniques de composants électroniques |
|
ADC10062 Fiches technique(PDF) 9 Page - National Semiconductor (TI) |
|
|
ADC10062 Fiches technique(HTML) 9 Page - National Semiconductor (TI) |
9 / 14 page Functional Description (Continued) section of the MSB Ladder has 1⁄8 of the total reference voltage across it, and each of the LSB resistors has 1/64 of the total reference voltage across it. Tap points across these resistors can be connected, in groups of sixteen, to the sixteen comparators at the right of the diagram. On the left side of the diagram is a string of seven resistors connected between V REF+ and VREF−. Six comparators com- pare the input voltage with the tap voltages on this resistor string to provide a low-resolution “estimate” of the input voltage. This estimate is then used to control the multiplexer that connects the MSB Ladder to the sixteen comparators on the right. Note that the comparators on the left needn’t be very accurate; they simply provide an estimate of the input voltage. Only the sixteen comparators on the right and the six on the left are necessary to perform the initial six-bit flash conversion, instead of the 64 comparators that would be required using conventional half-flash methods. To perform a conversion, the estimator compares the input voltage with the tap voltages on the seven resistors on the left. The estimator decoder then determines which MSB Ladder tap points will be connected to the sixteen compara- tors on the right. For example, assume that the estimator determines that V IN is between 11/16 and 13/16 of VREF. The estimator decoder will instruct the comparator MUX to con- nect the 16 comparators to the taps on the MSB ladder between 10/16 and 14/16 of V REF. The 16 comparators will then perform the first flash conversion. Note that since the comparators are connected to ladder voltages that extend beyond the range indicated by the estimator circuit, errors in the estimator as large as 1/16 of the reference voltage (64 LSBs) will be corrected. This first flash conversion pro- duces the six most significant bits of data — four bits in the flash itself, and 2 bits in the estimator. The remaining four LSBs are now determined using the same sixteen comparators that were used for the first flash conversion. The MSB Ladder tap voltage just below the input voltage (as determined by the first flash) is subtracted from the input voltage and compared with the tap points on the sixteen LSB Ladder resistors. The result of this second, four-bit flash conversion is then decoded, and the full 10-bit result is latched. Note that the sixteen comparators used in the first flash conversion are reused for the second flash. Thus, the multi- step conversion technique used in the ADC10061, ADC10062, and ADC10064 needs only a small fraction of the number of comparators that would be required for a traditional flash converter, and far fewer than would be used in a conventional half-flash approach. This allows the ADC10061, ADC10062, and ADC10064 to perform high-speed conversions without excessive power drain. Applications Information 1.0 MODES OF OPERATION The ADC10061, ADC10062, and ADC10064 have two basic digital interface modes. Figure 1 and Figure 2 are timing diagrams for the two modes. The ADC10062 and ADC10064 have input multiplexers that are controlled by the logic levels on pins S 0 and S1 when S/H goes low. Table 1 is a truth table showing how the input channnels are assigned. 01102014 FIGURE 3. Block Diagram of the Multistep Converter Architecture www.national.com 9 |
Numéro de pièce similaire - ADC10062 |
|
Description similaire - ADC10062 |
|
|
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 |