Datasheet

Data Sheet ADAS3023
TERMINOLOGY
Operating Input Voltage Range
Operating input voltage range is the maximum input voltage
range, including common-mode, which can be applied to the
input channels, IN0 to IN7, and COM.
Differential Input Voltage Range
Differential input voltage range is the maximum differential
full-scale input range. The value changes according to the
selected programmable gain setting.
Channel Off Leakage
Channel off leakage is the leakage current with the channel
turned off.
Channel On Leakage
Channel on leakage is the leakage current with the channel
turned on.
Common-Mode Rejection Ratio (CMRR)
CMRR is computed as the ratio of the signal magnitude of the
converted result, referred to input, in the converted result to the
amplitude of the common modulation signal applied to an input
pair, expressed in decibels. CMRR is a measure of the ability of
the ADAS3023 to reject signals, such as power line noise, that are
common to the inputs. This specification is tested and specified
for all input channels, IN0 to IN7, with respect to COM.
Transient Response
Transient response is a measure of the time required for the
ADAS3023 to properly acquire the input after a full-scale step
function is applied to the system.
Least Significant Bit (LSB)
The LSB is the smallest increment that can be represented by a
converter. For a fully differential input ADC with N bits of
resolution, the LSB expressed in volts is
N
REF
V
LSB
2
2
(V) =
Integral Nonlinearity Error (INL)
INL refers to the deviation of each individual code from a line
drawn from negative full scale through positive full scale. The
point used as negative full scale occurs ½ LSB before the first
code transition. Positive full scale is defined as a level 1½ LSB
beyond the last code transition. The deviation is measured from
the middle of each code to the true straight line (see Figure 37).
Differential Nonlinearity Error (DNL)
In an ideal ADC, code transitions are 1 LSB apart. DNL is the
maximum deviation from this ideal value. DNL is often specified in
terms of resolution for which no missing codes are guaranteed.
Offset Error
Ideally, the MSB transition occurs at an input level that is ½ LSB
above analog ground. The offset error is the deviation of the
actual transition from that point.
Gain Error
Ideally, the last transition (from 011 … 10 to 011 … 11) occurs
for an analog voltage 1½ LSB below the nominal full scale. The
gain error is the deviation in LSB (or percentage of full-scale
range) of the actual level of the last transition from the ideal
level after the offset error is removed. Closely related is the full-
scale error (also in LSB or percentage of full-scale range), which
includes the effects of the offset error.
Aperture Delay
Aperture delay is the measure of the acquisition performance. It
is the time between the rising edge of the CNV input and the point
at which the input signal is held for a conversion.
Dynamic Range
Dynamic range is the ratio of the rms value of the full scale to
the total rms noise measured with a −60 dBFS input signal applied
to the inputs. The value for dynamic range is expressed in decibels.
Signal-to-Noise Ratio (SNR)
SNR is the ratio of the rms value of the actual input signal to the
rms sum of all other spectral components below the Nyquist
frequency, excluding harmonics and dc. The value for SNR is
expressed in decibels.
Signal-to-(Noise + Distortion) Ratio (SINAD)
SINAD is the ratio of the rms value of the actual input signal to
the rms sum of all other spectral components below the Nyquist
frequency, including harmonics but excluding dc. The value for
SINAD is expressed in decibels.
Total Harmonic Distortion (THD)
THD is the ratio of the rms sum of the first five harmonic
components to the rms value of a full-scale input signal
expressed in decibels.
Spurious-Free Dynamic Range (SFDR)
SFDR is the difference, in decibels, between the rms amplitude
of the input signal and the peak spurious signal.
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