поискавой системы для электроныых деталей |
|
AD74111 датащи(PDF) 9 Page - Analog Devices |
|
AD74111 датащи(HTML) 9 Page - Analog Devices |
9 / 20 page REV. 0 AD74111 –9– ADC MODULATOR 64 f S 5th ORDER COMB FILTER HALF-BAND 8 f S 4 f S COMB COMPENSATION 2 f S HALF-BAND f S ADC RESULT LOW GROUP DELAY OUTPUT Figure 5a. ADC Filter Section DAC MODULATOR 128 f S 16 ZERO ORDER HOLD HALF-BAND FILTER 8 f S 4 f S ZERO ORDER HOLD SINC COMPENSATION FILTER 2 f S HALF-BAND– FILTER f S DAC INPUT LOW GROUP DELAY INPUT Figure 5b. DAC Filter Section ADC, CAPP, and CAPN Pins The ADC channel requires two external capacitors to act as charge reservoirs for the switched capacitor inputs of the sigma- delta modulator. These capacitors isolate the outputs of the PGA stage from glitches generated by the sigma-delta modulator. The capacitor also forms a low-pass filter with the output impedance of the PGA (approximately 124 Ω), which helps to isolate noise from the modulator engine. The capacitors should be of good quality, such as NPO or polypropylene film, with values from 100 pF to 1 nF and should be connected to AGND. Peak Readback The AD74111 can store the highest ADC value to facilitate level adjustment of the input signal. Programming the Peak Enable bit in Control Register E with a 1 will enable ADC Peak Level Reading. The peak value is stored as a 6-bit number from 0 dB to –63 dB in 1 dB steps. Reading Control Register F will give the highest ADC value since the bit was set. The ADC peak register is automatically cleared after reading. Decimator Section The digital decimation filter has a pass-band ripple of 0.2 mdB and a stop-band attenuation of 120 dB. The filter is an FIR type with a linear phase response. The group delay at 48 kHz is 910 µs. Output sample rates up to 48 kHz are supported. Input Signal Swing The ADC input has an input range of 0.5 V rms/1.414 V p-p about a bias point equal to VREFCAP. Figure 6 shows a typical input filter circuit for use with the AD74111. VIN VAGND 1.414V p-p 51 10nF NPO 47 F Figure 6. Typical Input Circuit DAC Section The AD74111 DAC channel has a single-ended, analog output. The DAC has independent software controllable Mute and Volume Control functions. Control Register G controls the attenuation factor for the DAC. This register is 10 bits wide, giving 1024 steps of attenuation. The AD74111 output channel employs a multibit sigma-delta conversion technique that provides a high quality output with system filtering implemented on-chip. Output Signal Swing The DAC has an output range of 0.5 V rms/1.414 V p-p about a bias point equal to VREFCAP (see Figure 7). VREFCAP 1.414V p-p 820 2n2F NPO VOUT Figure 7. Typical Output Circuit Low Group Delay It is possible to bypass much of the digital filtering by enabling the Low Group Delay function in Control Register C. By reduc- ing the amount of filtering the AD74111 applies to input and output samples, the time delay between the sampling interval and when the sample is available is greatly reduced. This can be of benefit in applications such as telematics, where minimal time delays are important. When the Low Group Delay function is enabled, the sample rate becomes IMCLK/128. Reference The AD74111 features an on-chip reference whose nominal value is 1.125 V. A 100 nF ceramic and 10 µF tantalum capacitor applied at the REFCAP pin are necessary to stabilize the reference. (See Figure 8.) REFCAP 0.1 F 10 F Figure 8. Reference Decoupling If required, an external reference can be used as the reference source of the ADC and DAC sections. This may be desirable in situations where multiple devices are required to use the same value of reference or because of a better temperature coefficient specification. The internal reference can be disabled via Control Register A and the external reference applied at the REFCAP pin (see Figure 9). External references should be of a suitable value such that the voltage swing of the inputs or outputs is not affected by being too close to the power supply rails and should be adequately decoupled. |
Аналогичный номер детали - AD74111 |
|
Аналогичное описание - AD74111 |
|
|
ссылки URL |
Конфиденциальность |
ALLDATASHEETRU.COM |
Вашему бизинису помогли Аллдатащит? [ DONATE ] |
Что такое Аллдатащит | реклама | контакт | Конфиденциальность | обмен ссыками | поиск по производителю 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 |