Electronic Components Datasheet Search |
|
AD974AN Datasheet(PDF) 8 Page - Analog Devices |
|
AD974AN Datasheet(HTML) 8 Page - Analog Devices |
8 / 20 page REV. A AD974 –8– can be read after the conversion is complete. The external clock can be either a continuous or discontinuous clock. A discontinu- ous clock can be either normally low or normally high when inactive. In the case of the discontinuous clock, the AD974 can be configured to either generate or not generate a SYNC output (with a continuous clock a SYNC output will always be produced). Each of the methods will be described in the following sections and are illustrated in Figures 4 through 9. It should be noted that all timing diagrams assume that the receiving device is latching data on the rising edge of the external clock. If the falling edge of DATACLK is used then, in the case of a discon- tinuous clock, one less clock pulse is required than shown in Figures 4 through 7 to latch in a 16-bit word. Note that data is valid on the falling edge of a clock pulse (for t13 greater than t18) and the rising edge of the next clock pulse. The AD974 provides error correction circuitry that can correct for an improper bit decision made during the first half of the conversion cycle. Normally the occurrence of an incorrect bit decision during a conversion cycle is irreversible. This error occurs as a result of noise during the time of the decision or due to insufficient settling time. As the AD974 is performing a conversion it is important that transitions not occur on digital input/output pins or degradation of the conversion result could occur. This is particularly important during the second half of the conversion process. For this reason it is recommended that when an external clock is being provided it be a discontinuous clock that is not toggling during the time that BUSY is low or, more importantly, that it does not transition during the latter half of BUSY low. EXTERNAL DISCONTINUOUS CLOCK DATA READ AFTER CONVERSION WITH NO SYNC OUTPUT GENERATED Figure 4 illustrates the method by which data from conversion “n” can be read after the conversion is complete using a discon- tinuous external clock without the generation of a SYNC output. After a conversion is complete, indicated by BUSY returning high, the result of that conversion can be read while CS is Low and R/C is high. In this mode CS can be tied low. The MSB will be valid on the first falling edge and the second rising edge of DATACLK. The LSB will be valid on the 16th falling edge and the 17th rising edge of DATACLK. A mini- mum of 16 clock pulses are required for DATACLK if the receiving device will be latching data on the falling edge of DATACLK. A minimum of 17 clock pulses are required for DATACLK if the receiving device will be latching data on the rising edge of DATACLK. The advantage of this method of reading data is that data is not being clocked out during a conversion and therefore conversion performance is not degraded. When reading data after the conversion is complete, with the highest frequency permitted for DATACLK (15.15 MHz), the maximum possible throughput is approximately 195 kHz, and not the rated 200 kHz. EXT DATACLK R/ C BUSY SYNC DATA t12 0 12 3 14 15 16 t13 t14 t1 t2 t21 t18 t18 BIT 15 (MSB) BIT 14 BIT 13 BIT 1 BIT 0 (LSB) Figure 4. Conversion and Read Timing Using an External Discontinuous Data Clock (EXT/ INT Set to Logic High, CS Set to Logic Low) |
Similar Part No. - AD974AN |
|
Similar Description - AD974AN |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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 |