CS4329 Datasheet, PDF (12/36 Pages) Cirrus Logic – 20-Bit, Stereo D/A Converter for Digital Audio

CS4329
is changed, the CS4390 will reset. Power is applied
to the internal voltage reference, the D/A convert-
ers, switched-capacitor filters and the DAC will
then enter a calibration mode to properly set the
common mode bias voltage and minimize the dif-
ferential offset. This initialization and calibration
sequence requires approximately 2700 cycles of
LRCK.
A offset calibration can also be invoked by taking
the Format select pins, DIF0, DIF1 and DIF2, to a
logic 1 as shown in Table 2. During calibration, the
differential outputs are shorted together and the
common-mode voltage appears at the output with
approximately an 8 kohm output impedance. Fol-
lowing calibration, the analog output impedance
becomes less than 10 ohms and the common mode
voltage will move to approximately 2.2 V .
The CS4329 will enter the power-down mode,
within 1 period of LRCK, if either MCLK or
LRCK is removed. The initialization sequence, as
described above, occurs when MCLK and LRCK
are restored.
Combined Digital and Analog Filter
Response
The frequency response of the combined analog
switched-capacitor and digital filters is shown in
Figures 9, 10 and 11. The overall response is clock
dependent and will scale with Fs. Note that the re-
sponse plots have been normalized to Fs and can be
de-normalized by multiplying the X-axis scale by
Fs, such as 48 kHz.
Analog Output and Filtering
The analog output should be operated in a differen-
tial mode which allows for the cancellation of com-
mon mode errors including noise, distortion and
offset voltage. Each output will produce a nominal
2.83 Vpp (1 Vrms) output for a full scale digital in-
put which equates to a 5.66 Vpp (2Vrms) differen-
tial signal as shown in Figure 12.
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Frequency (x Fs)
Figure 9. CS4329 Combined Digital and Analog Filter
Stopband Rejection
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0.45
0.48
0.51
0.54
0.57
0.60
Frequency (x Fs)
Figure 10. CS4329 Combined Digital and Analog
Filter
0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
0.46 0.47 0.48 0.49 0.50 0.51 0.52
Frequency (x Fs)
Figure 11. Combined Digital and Analog Filter
12
DS153F1