CS4265_07 Datasheet, PDF (28/56 Pages) Cirrus Logic – 104 dB, 24-Bit, 192 kHz Stereo Audio CODEC

CS4265
clocking change, the DAC outputs will always be in a zero-data state. If non-zero serial audio input is
present at the time of switching, a slight click or pop may be heard as the DAC output automatically goes
to its zero-data state.
4.8 DAC Serial Data Input Multiplexer
The CS4265 contains a 2-to-1 serial data input multiplexer. This allows two separate data sources to be
input into the DAC without the use of any external multiplexing components. “Section 6.6.1 “DAC SDIN
Source (Bit 7)” on page 39” describes the control port settings necessary to control the multiplexer.
4.9 De-Emphasis Filter
The CS4265 includes on-chip digital de-emphasis optimized for a sample rate of 44.1 kHz. The filter re-
sponse is shown in Figure 13. The frequency response of the de-emphasis curve scales proportionally with
changes in sample rate, Fs. Please see Section 6.3.3 “De-Emphasis Control (Bit 1)” on page 37 for de-em-
phasis control.
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.
Gain
dB
0dB
T1=50 µs
-10dB
T2 = 15 µs
F1
3.183 kHz
F2 Frequency
10.61 kHz
Figure 13. De-Emphasis Curve
4.10 Internal Digital Loopback
The CS4265 supports an internal digital loopback mode in which the output of the ADC is routed to the input
of the DAC. This mode may be activated by setting the LOOP bit in the Signal Selection register (See “Signal
Selection - Address 06h” section on page 39).
When this bit is set, the status of the DAC_DIF[1:0] bits in register 03h will be disregarded by the CS4265.
Any changes made to the DAC_DIF[1:0] bits while the LOOP bit is set will have no impact on operation until
the LOOP bit is cleared, at which time the Digital Interface Format of the DAC will operate according to the
format selected by the DAC_DIF[1:0] bits. While the LOOP bit is set, data will be present on the SDOUT pin
in the format selected by the ADC_DIF bit in register 04h.
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