Datasheet

2003 Apr 10 16
NXP Semiconductors Preliminary specification
Stereo audio codec with SPDIF interface UDA1355H
Table 7 Interpolation filter characteristics
7.7.3 D
IGITAL MIXER
The UDA1355H has a digital mixer inside the interpolator.
The digital mixer can be used as a cross over or a selector.
A functional block diagram of the mixer mode is shown in
Fig.9. This mixer can be used in microcontroller mode
only.
The UDA1355H can be set to the mixer mode by setting
bit MIX = 1. In the mixer mode, there are three volume and
mute controls available: for source 1, for source 2 and for
the master (sum) signal. All three volume ranges can be
controlled in 0.25 dB steps.
To prevent clipping inside the mixer, the signals are scaled
with −6 dB before mixing, therefore the sum of the two
signals is always equal to or lower than 0 dB. After the
mixing there is a 6 dB gain in the master volume control.
This means that at the analog output the signal can clip,
but the clipping can be undone by decreasing the master
volume control.
The output of the mixer is available via the I
2
S-bus output
or via the SPDIF output. The output signal of the mixer is
scaled to a maximum of 0 dB, so the digital output can
never clip.
ITEM CONDITIONS VALUE (dB)
Pass-band ripple 0 to 0.45f
s
±0.035
Stop band >0.55f
s
−60
Dynamic range 0 to 0.4535f
s
140
handbook, halfpage
MGU832
gain
(dB)
−6
−10
−2
6
2
10
−8
−4
4
0
8
11010
2
10
3
f (Hz))
Fig.7 Resonant bass boost example 1.
f
c
=70Hz
f
s
=44.1kHz
Peak gain = 10 dB
Shape factor = 1.4142
handbook, halfpage
MGU831
gain
(dB)
−6
−10
−2
6
2
10
−8
−4
4
0
8
11010
2
10
3
f (Hz))
Fig.8 Resonant bass boost example 2.
f
c
=70Hz
f
s
=44.1kHz
Peak gain = 10 dB
Shape factor = 1.4142