CS4270 Cirrus Logic, CS4270 Datasheet - Page 27

• Manufacturer Part Number: CS4270
• Description: 192 kHz Stereo Audio CODEC
• Manufacturer: Cirrus Logic

DS686A1
5.2.8 De-Emphasis
5.2.9 Oversampling Modes
5.3
De-Emphasis Filter
One de-emphasis mode is available via the Control Port and is optimized for 44.1 kHz sampling rate.
The CS4270 operates in one of three oversampling modes based on the input sample rate. Mode selec-
tion is determined by the FM_&_M/S_Mode[1:0] bits in the Functional Mode register (03h). Single-Speed
mode supports input sample rates up to 54 kHz and uses a 128x oversampling ratio. Double-Speed mode
supports input sample rates up to 108 kHz and uses an oversampling ratio of 64x. Quad-Speed mode
supports input sample rates up to 216 kHz and uses an oversampling ratio of 32x. See
trol Port Mode settings.
The CS4270 includes on-chip digital de-emphasis.
to 44.1 kHz. The frequency response of the de-emphasis curve will scale proportionally with changes in
sample rate, Fs. Please see
Section 5.2.8
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.
for control port mode.
-10dB
Gain
0dB
dB
Section 5.1.7
Figure 11. De-Emphasis Curve
3.183 kHz
T1=50 µs
F1
for the desired de-emphasis control for Stand-Alone mode and
Figure 11
10.61 kHz
F2
shows the de-emphasis curve for Fs equal
T2 = 15 µs
Frequency
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Table 10
CS4270
for Con-
27