AD7694 Analog Devices, AD7694 Datasheet - Page 8

• Manufacturer Part Number: AD7694
• Manufacturer: Analog Devices

Specifications of AD7694

• Resolution (bits): 16bit
• # Chan: 1
• Sample Rate: 250kSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Uni
• Ain Range: (Vref) p-p,Uni (Vref)
• Adc Architecture: SAR
• Pkg Type: SOP

AD7694
TERMINOLOGY
Integral Nonlinearity Error (INL)
Linearity error refers to the deviation of each individual code
from a line drawn from negative full scale to 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
1 ½ LSB beyond the last code transition. The deviation is
measured from the middle of each code to the true straight line
(see Figure 19).
Differential Nonlinearity Error (DNL)
In an ideal ADC, code transitions are 1 LSB apart. DNL is the
maximum deviation from this ideal value. It is often specified in
terms of resolution for which no missing codes are guaranteed.
Offset Error
The first transition should occur at a level ½ LSB above analog
ground (38.1 μV for the 0 V to 5 V range). The offset error is
the deviation of the actual transition from that point.
Gain Error
The last transition (from 111...10 to 111...11) should occur for
an analog voltage 1 ½ LSB below the nominal full scale
(4.999886 V for the 0 V to 5 V range). The gain error is the
deviation of the actual level of the last transition from the ideal
level after the offset has been adjusted out.
Spurious-Free Dynamic Range (SFDR)
The difference, in decibels (dB), between the rms amplitude of
the input signal and the peak spurious signal.
Rev. A | Page 8 of 16
Effective Number of Bits (ENOB)
ENOB is a measurement of the resolution with a sine wave
input. It is related to S/(N + D) by
and is expressed in bits.
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 and is
expressed in dB.
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 dB.
Signal-to-(Noise + Distortion) Ratio (S/[N + D])
S/(N+D) 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 S/(N+D) is expressed in dB.
Aperture Delay
Aperture delay is a measure of the acquisition performance and
the time between the rising edge of the CNV input and the time
the input signal is held for conversion.
Transient Response
The time required for the ADC to accurately acquire its input
after a full-scale step function is applied.
ENOB = (S/[N + D]
dB
− 1.76)/6.02