Cirrus Logic CS4392 - Manual (Page 12)

CS4392
12 DS459PP3
3.7 De-Emphasis
The device includes on-chip digital de-emphasis. Figure 7 shows the de-emphasis curve for F
S
equal to
44.1 kHz. The frequency response of the de-emphasis curve will scale proportionally with changes in sam-
ple rate, F
s
. Please see Table 5 for the desired de-emphasis control for Stand-alone mode and Table 10 for
control port mode.
The de-emphasis feature is included to accommodate audio recordings that utilize 50/15 µS pre-emphasis
equalization as a means of noise reduction.
De-emphasis is only available in Single Speed Mode.
3.8 Oversampling Modes
The CS4392 operates in one of three oversampling modes based on the input sample rate. Mode selection
is determined by the M3 and M2 pins in Stand-Alone mode or the FM bits in Control Port mode. Single-
Speed mode supports input sample rates up to 50 kHz and uses a 128x oversampling ratio. Double-Speed
mode supports input sample rates up to 100 kHz and uses an oversampling ratio of 64x. Quad-Speed mode
supports input sample rates up to 200 kHz and uses an oversampling ratio of 32x
M3 M2 DESCRIPTION
0 0 Single-Speed without De-Emphasis (4 to 50 kHz sample rates)
0 1 Single-Speed with 44.1kHz De-Emphasis
1 0 Double-Speed (50 to 100 kHz sample rates)
1 1 Quad-Speed (100 to 200 kHz sample rates)
Table 6. Mode Selection, Stand-Alone Mode Options
Gain
dB
-10dB
0dB
Frequency
T2 = 15 µs
T1=50 µs
F1 F2
3.183 kHz 10.61 kHz
Figure 7. De-Emphasis Curve
M2
(DEM)
DESCRIPTION FIGURE
0 No De-Emphasis
1 De-Emphasis Enabled 7
Table 5. De-Emphasis Select, Stand-Alone Mode