поискавой системы для электроныых деталей |
|
AD7721 датащи(PDF) 8 Page - Analog Devices |
|
AD7721 датащи(HTML) 8 Page - Analog Devices |
8 / 16 page AD7721 REV. A –8– TERMINOLOGY Integral Nonlinearity This is the maximum deviation of any code from a straight line passing through the endpoints of the transfer function. The end- points of the transfer function are zero scale (not to be con- fused with bipolar zero), a point 0.5 LSB below the first code transition (100 . . . 00 to 100 . . . 01 in bipolar mode and 000 . . . 00 to 000 . . . 01 in unipolar mode) and full scale, a point 0.5 LSB above the last code transition (011 . . . 10 to 011 . . . 11 in bipolar mode and 111 . . . 10 to 111 . . . 11 in unipolar mode). The error is expressed in LSBs. Differential Nonlinearity This is the difference between the measured and the ideal 1 LSB change between two adjacent codes in the ADC. Common Mode Rejection Ratio The ability of a device to reject the effect of a voltage applied to both input terminals simultaneously—often through variation of a ground level—is specified as a common-mode rejection ratio. CMRR is the ratio of gain for the differential signal to the gain for the common-mode signal. Unipolar Offset Error Unipolar offset error is the deviation of the first code transition from the ideal VIN1 voltage which is (VIN2 + 0.5 LSB) when operating in the unipolar mode. Bipolar Offset Error This is the deviation of the midscale transition (111 . . . 11 to 000 . . . 00) from the ideal VIN1 voltage which is (VIN2 – 0.5 LSB) when operating in the bipolar mode. Unipolar Full-Scale Error Unipolar full-scale error is the deviation of the last code transition (111 . . . 10 to 111 . . . 11) from the ideal VIN1 voltage which is (VIN2 + VREFIN – 3/2 LSBs). Bipolar Full-Scale Error The bipolar full-scale error refers to the positive full-scale error and the negative full-scale error. The positive full-scale error is the deviation of the last code transition (011 . . . 10 to 011 . . . 11) from the ideal VIN1 voltage which is (VIN2 + VREFIN/2 – 3/2 LSB). The negative full-scale error is the deviation of the first code transi- tion (100 . . . 00 to 100 . . . 01) from the ideal VIN1 voltage which is (VIN2 – VREFIN/2 + 0.5 LSB). Signal to (Noise + Distortion) Signal to (Noise + Distortion) is measured signal to noise at the output of the ADC. The signal is the rms magnitude of the funda- mental. Noise is the rms sum of all the nonfundamental signals up to half the sampling frequency (fCLK/2) but excluding the dc com- ponent. Signal to (Noise + Distortion) is dependent on the num- ber of quantization levels used in the digitization process; the more levels, the smaller the quantization noise. The theoretical Signal to (Noise + Distortion) ratio for a sine wave input is given by Signal to (Noise + Distortion) = (6.02 N + 1.76) dB where N is the number of bits. Thus, for an ideal 12-bit converter, Signal to (Noise + Distortion) = 74 dB. Total Harmonic Distortion Total Harmonic Distortion (THD) is the ratio of the rms sum of harmonics to the rms value of the fundamental. For the AD7721, THD is defined as THD = 20 log (V 2 2 +V 3 2 +V 4 2 +V 5 2 +V 6 2 ) V 1 where V1 is the rms amplitude of the fundamental and V2, V3, V4, V5 and V6 are the rms amplitudes of the second through the sixth harmonic. USING THE AD7721 ADC Differential Inputs The AD7721 uses differential inputs to provide common-mode noise rejection. In the bipolar mode configuration, the analog input range is ±1.25 V. The designed code transitions occur midway between successive integer LSB values. The output code is 2s complement binary with 1 LSB = 0.61 mV in paral- lel mode and 38 µV in serial mode. The ideal input/output transfer function is illustrated in Figure 2. In the unipolar mode, the analog input range is 0 V to 2.5 V. Again, the designed code transitions occur midway between suc- cessive integer LSB values. The output code is straight binary with 1 LSB = 0.61 mV in parallel mode and 38 µV in serial mode. The ideal input/output transfer function is shown in Figure 3. 0V 100...000 011...111 000...000 011...110 000...010 000...001 111...111 111...110 100...001 DIFFERENTIAL INPUT VOLTAGE (VIN1–VIN2) OUTPUT CODE AD7721 –REF IN/2 +REF IN/2–1LSB Figure 2. AD7721 Bipolar Mode Transfer Function 000...000 000...010 000...001 111...111 111...110 DIFFERENTIAL INPUT VOLTAGE (VIN1–VIN2) OUTPUT CODE AD7721 111...101 111...100 000...011 0V REF IN–1LSB Figure 3. AD7721 Unipolar Mode Transfer Function |
Аналогичный номер детали - AD7721 |
|
Аналогичное описание - AD7721 |
|
|
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 |