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Nom de la pièce  Description 
ADUCM330WFS Datasheet(Fiches technique) 15 Page  Analog Devices 

15 page Data Sheet ADuCM330WFS/ADuCM331WFS Rev. A  Page 15 of 17 TERMINOLOGY Conversion Rate The conversion rate specifies the rate at which an output result is available from the ADC after the ADC has settled. The ΣΔ conversion techniques used on this device mean that, although the ADC frontend signal is oversampled at a relatively high sample rate, a subsequent digital filter is used to decimate the output. Use of a digital filter provides a valid 20bit data conversion result at output rates from 4 Hz to 8 kHz. When software switches from one input to another on the same ADC, the digital filter must first be cleared and then allowed to average a new result. Depending on the configuration of the ADC and the type of filter, this averaging can require multiple conversion cycles. Integral Nonlinearity (INL) INL is the maximum deviation of any code from a straight line passing through the endpoints of the transfer function. The endpoints of the transfer function are zero scale, which is a point ½ LSB below the first code transition, and full scale, which is a point ½ LSB above the last code transition (111…110 to 111…111). The error is expressed as a percentage of full scale. Positive INL is the deviation from a straight line through ½ LSB above midscale code transition to ½ LSB above the last code transition. Negative INL is the deviation from a straight line from a point ½ LSB below the first code transition to a point ½ LSB above the midscale code transition. No Missing Codes No missing codes is a measure of the differential nonlinearity of the ADC. The error is expressed in bits and specifies the number of codes (ADC results) as 2N bits, where N equals no missing codes, guaranteed to occur through the full ADC input range. Offset Error Offset error is the deviation of the first code transition ADC input voltage from the ideal first code transition. Offset Error Drift Offset error drift is the variation in absolute offset error with respect to temperature. This error is expressed as LSB/°C or nV/°C. Gain Error Gain error is a measure of the span error of the ADC. It is a measure of the difference between the measured and the ideal span between any two points in the transfer function. Output Noise The output noise is specified as the standard deviation (or 1 × Σ) of ADC output code distribution collected when the ADC input voltage is at a dc voltage. It is expressed as µV rms or nV rms. The output, or rms noise, is used to calculate the effective resolution of the ADC as defined by the following equation, measured in bits: Effective Resolution = log2(FullScale Range/rms Noise) The peaktopeak noise is defined as the deviation of codes that fall within 6.6 × Σ of the distribution of ADC output codes collected when the ADC input voltage is at dc. The peakto peak noise is therefore calculated as 6.6 × the rms noise. The peaktopeak noise can be used to calculate the ADC noise free code resolution for which there is no code flicker within a 6.6 × Σ limit as defined by the following equation, measured in bits: Noise Free Code Resolution = log2(FullScale Range/Peak toPeak Noise) 
