
PARAMETER DEFINITIONS
Resolution
The number of bits in the input words to the DACs, and in the output words in
the ADCs
Differential Nonlinearity
The worst case deviation from the ideal codewidth, expressed in LSBs.
Total Dynamic Range
The ratio between the DAC full scale output and the noise floor with the DAC
muted. Units are in dB
Total Harmonic Distortion + Noise
(THD+N)
THD+N is the ratio of the rms value of the input signal to the rms sum of all
other spectral components within the measurement bandwidth (10 Hz to 20
kHz). THD+N is expressed in dB.
Total Harmonic Distortion (THD)
THD is the ratio of the text signal amplitude to the rms sum of all the in-band
harmonics of the text signal.
Instantaneous Dynamic Range
The S/(N+D) with a 1kHz, -60dB input signal, with 60dB added to compensate
the small input signal. Use of a small input signal reduces the harmonic
distortion components of the noise to insignificance. Units are dB
Interchannel Isolation
The amount of 1kHz signal present on the output of the grounded input
channel with 1kHz, 0dB signal present on the other channel. Units are 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 are in dB.
Frequency Response
worst case variations in output signal level versus frequency over 10 Hz to 20
kHz. Units in dB
Offset Error
For the ADCs, the deviation in LSBs of the output from mid-scale with the
selected input grounded. For the DACs, the deviation of the output from zero
with mid-scale input code. Units are in volt
ADC PERFORMANCE Some of the relevant ADC parameters are reported in the following table:
(T = 25°C, AVDD = 3.3V, measurement bandwidth 10Hz to 20KHz, A-Weighted Filter.)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
Maximum input level (1)
1
Vrms
Sample rate
32
48
KHz
Frequency Response
@ 20KHz with fs = 44.1KHz
-3
dB
Instant Dynamic Range
-60dB analog input
90
93
dB
SNR
1KHz; -3dB analog input
90
93
dB
(THD + N)/S
-3dB analog input
-85
dB
PSRR
0.1Vp @ 1KHz
45
dB
Input Impedance
10
30
K
Crosstalk
1Vrms input @ 15KHz
70
dB
Gain mismatch between four
input
@ 1KHz
-0.5
0.5
dB
CMRR
@ 1KHz
40
dB
CM Input range (2)
100
mV
(1) Corresponding to 2VRMS Maximum Differential Input.
(2) The ADC cell runs on a 3.3V power supply, as a consequence it is not possible to move the CM around half Vdd (~1.6V) 1.6V up and down
(rail to rail).
TDA7531
3/11