CS4239 Datasheet, PDF (92/98 Pages) Cirrus Logic – CrystalClear™ Portable ISA Audio System

CS4239
CrystalClear^TM Portable ISA Audio System
PARAMETER DEFINITIONS
Frequency Response
Frequency Response is the deviation in signal level verses frequency. The 0 dB reference point
is 1 kHz. The amplitude corner, Ac, lists the maximum deviation in amplitude above and below
the 1 kHz reference point. The listed minimum and maximum frequencies are guaranteed to be
within the Ac from minimum frequency to maximum frequency inclusive.
Total Dynamic Range
TDR is the ratio of the RMS sum of the lowest obtainable noise floor, in the presence of a
signal, divided by the RMS full-scale signal level. The lowest obtainable noise floor is defined
as the noise floor measured with the attenuation bits for the volume control at full attenuation -
without muting. Measured over a 20 Hz to 20 kHz bandwidth with units in dB FS A. (dB FS is
defined as dB relative to full-scale. The "A" indicates an A weighting filter was used.)
Instantaneous Dynamic Range or Dynamic Range
IDR or DR is the ratio of the RMS sum of the noise floor, in the presence of a signal, divided
by the RMS full-scale signal level, available at any instant in time (no change in gain settings
between measurements). Measured over a 20 Hz to 20 kHz bandwidth with units in dB FS A.
(dB FS is defined as dB relative to full-scale. The "A" indicates an A weighting filter was
used.)
Total Harmonic Distortion plus Noise
THD+N is the ratio of the RMS sum of all non-fundamental frequency components, divided by
the RMS full-scale signal level. Tested using a -3 dB FS input signal. Measured over a 20 Hz to
20 kHz bandwidth with units in dB FS A. (dB FS is defined as dB relative to full-scale. The
"A" indicates an A weighting filter was used.)
Interchannel Isolation
The ratio of signal level on the tested channel divided by the stimulus channel level. For inputs,
the tested input channel is terminated with 50 Ω. For outputs, the tested channel is fed digital
zeros. Units in dB.
Interchannel Gain Mismatch
For the ADCs, the difference in input voltage to get an equal code on both channels. For the
DACs, the difference in output voltages for each channel when both channels are fed the same
code. Units in dB.
PATHS:
A-D-PC: Analog in, through ADC, onto PC bus
PC-D-A: PC bus, through DAC, to analog out
A-A: Analog in to Analog out (analog output mixer)
Detailed information on audio testing and paths can be found in Personal Computer Audio Quality
Measurements document by Dr. Steven Harris and Clif Sanchez, located at the following web address:
http://www.cirrus.com/products/papers/meas/meas.html.
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