CS4218 Datasheet, PDF (36/44 Pages) Cirrus Logic – 16-Bit Stereo Audio Codec

CS4218
PARAMETER DEFINITIONS
Resolution
The number of bits in the input words to the DACs, and in the output words from the ADCs.
Differential Nonlinearity
The worst case deviation from the ideal codewidth. Units in LSB.
Total Dynamic Range
TDR is the ratio of the rms value of a full scale signal to the lowest obtainable noise floor. It is
measured by comparing a full scale signal to the lowest noise floor possible in the codec (i.e.
attenuation bits for the DACs at full attenuation). Units in dB.
Instantaneous Dynamic Range
IDR is the ratio of a full-scale rms signal to the rms noise available at any instant in time,
without changing the input gain or output attenuation settings. It is measured using S/(N+D)
with a 1 kHz, -60 dB input signal, with 60 dB added to compensate for the small input signal.
Use of a small input signal reduces the harmonic distortion components to insignificance when
compared to the noise. Units in dB.
Total Harmonic Distortion
THD is the ratio of the rms value of a signal’s first five harmonic components to the rms value
of the signals fundamental component. THD is calculated using an input signal which is 3dB
below typical full-scale, and is referenced to typical full-scale.
Interchannel Isolation
The amount of 1 kHz signal present on the output of the grounded input channel, with 1 kHz
0 dB signal present on the other channel. Units in dB.
Interchannel Gain Mismatch
For the ADCs, the difference in input voltage that generates the full scale code for each
channel. For the DACs, the difference in output voltages for each channel with a full scale
digital input. Units in dB.
Frequency Response
Worst case variation in output signal level versus frequency over the passband. Tested over the
frequency band of 10 Hz to 20 kHz, with the sample frequency of 48 kHz. Units in dB.
Step Size
Typical delta between two adjacent gain or attenuation values. Units in dB.
Absolute Gain/Attenuation Step Error
The deviation of a gain or attenuation step from a straight line passing through the
no-gain/attenuation value and the full-gain/attenuation value (i.e. end points). Units in dB.
Offset Error
For the ADCs, the deviation of the output code from the mid-scale with the selected input at
REFBUF. For the DACs, the deviation of the output from REFBUF with mid-scale input code.
Units in LSB’s for the ADCs and volts for the DACs.
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