Datasheet ISOSD61 (STMicroelectronics) - 10

ISOSD61 Terminology 4 Terminology Differential Nonlinearity (DNL)
DNL is the difference between the measured and the ideal 1 LSB change between any two adjacent codes in the ADC.
Integral Nonlinearity (INL)
INL is the maximum deviation from a straight line passing through the endpoints of the ADC transfer function.
Offset error
Offset error is the deviation of the center scale code from the ideal scale code corresponding to 0 V differential input voltage.
Gain error
The gain is the derivative of the digital output code vs. the input signal. Graphically, for the output code vs. input signal transfer function (an ideal straight line), the gain is the slope of such function. The gain error is the % difference between the measured slope and the expected one.
Signal-to-Noise-and-Distortion Ratio (SINAD or SNDR)
SINAD is the measured ratio of signal to noise and distortion at the output of the ADC. The signal is the RMS value of the sine wave, and noise is the RMS sum of all non-fundamental AC signals up to half the sampling frequency (fS / 2), including harmonics.
Signal-to-Noise Ratio (SNR)
SNR is the measured ratio of signal to noise at the output of the ADC. The signal is the RMS amplitude of the fundamental. Noise is the RSM sum of all non-fundamental AC signals up to half the sampling frequency (fS/2). The ratio is dependent on the number of quantization levels in the conversion: the greater the number of levels, the smaller the quantization noise. The theoretical signal-to-noise ratio for an ideal N-bit converter with a sine wave input is given by Signal-to-Noise Ratio = (6.02N + 1.76) [dB] Therefore, for a 12-bit converter, the SNR is 74 dB.
Isolation transient immunity
The isolation transient immunity specifies the rise and fall speed of a transient pulse applied across the isolation barrier, beyond which clock or data is corrupted.
Total Harmonic Distortion (THD)
THD is the ratio of the RMS sum of harmonics to the fundamental. The THD stated in this datasheet is defined as: V 2 + V 2+V 2 + V 2 + V 2 THD = 20log 2 3 4 5 6 V1 where: V1 is the RMS amplitude of the fundamental. V2, V3, V4, V5, and V6 are the RMS amplitudes of the second through the sixth harmonics. The result is in dB.
Spurious Free Dynamic Range (SFDR)
SFDR is defined as the ratio of the RMS value of the AC Noise Peak (up to fS / 2) to the RMS value of the fundamental.
Effective Number of Bits (ENOB)
ENOB is defined by: ENOB = (SINAD - 1.76) / 6.02 [bits]
Noise free code resolution
Noise free code resolution represents the resolution in bits for which there is no code flicker. The noise free code resolution for an N-bit converter is defined as Noisefree code resolution = log 2 N  2 Peak − to − Peak Noise bits The peak-to-peak noise in LSBs is measured with VIN+ = VIN− = 0 V.
Common-Mode Rejection Ratio (CMRR) DS13605
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Rev 3 page 10/23
Document Outline Cover image Product status link / summary Features Application Description 1 Device overview 2 Pin description 3 Device specifications 4 Terminology 5 Theory of operation 6 Package description 7 Ordering information Revision history Contents List of tables List of figures