Texas Instruments SRC4382 Evaluation Module (EVM) and USB motherboard SRC4382EVM-PDK SRC4382EVM-PDK Datenbogen
Produktcode
SRC4382EVM-PDK
www.ti.com
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-1
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Frequency (Hz)
10
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Attenuation(dB)
f = 192kHz
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Slow Mode
Fast Mode
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Attenuation(dB)
f = 192kHz
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Slow Mode
Fast Mode
SBFS030C – JANUARY 2006 – REVISED SEPTEMBER 2007
The input and output servo-loop frequency responses are shown in
and
, respectively. The
filter response for each servo loop rolls off at 80dB per decade. The servo loop corner frequencies scale
proportionally with input or output sampling rates. The low corner frequency and sharp roll-off provide excellent
jitter attenuation for the SRC block.
proportionally with input or output sampling rates. The low corner frequency and sharp roll-off provide excellent
jitter attenuation for the SRC block.
Figure 73. Input Digital Servo-Loop Frequency Response
Figure 74. Output Digital Servo-Loop Frequency Response
The SRC includes output soft muting and digital attenuation functions, providing artifact-free muting and output
level control for the SRC output data. The mute function forces the SRC output data low by stepping the output
attenuation from the current setting to an all-zero data output state. The mute function may be controlled by the
MUTE input (pin 14), or the MUTE bit in control register 0x2D. Both the pin and control bit are active high, with
the signals being combined by a logic OR function internally to generate the SRC output mute control signal. The
MUTE control bit in control register 0x2D is disabled by default.
level control for the SRC output data. The mute function forces the SRC output data low by stepping the output
attenuation from the current setting to an all-zero data output state. The mute function may be controlled by the
MUTE input (pin 14), or the MUTE bit in control register 0x2D. Both the pin and control bit are active high, with
the signals being combined by a logic OR function internally to generate the SRC output mute control signal. The
MUTE control bit in control register 0x2D is disabled by default.
The digital attenuation is programmable over a 0dB to –127.5dB range in 0.5dB steps, and may be controlled
independently for the Left and Right channels. The attenuation level is set using control registers; by default, the
level is 0dB. A tracking function is available, allowing the Left and Right channel attenuation data to be set to the
same value by simply programming the Left channel attenuation register. The tracking mode is enabled or
disabled using a control register bit. The tracking function is disabled by default.
independently for the Left and Right channels. The attenuation level is set using control registers; by default, the
level is 0dB. A tracking function is available, allowing the Left and Right channel attenuation data to be set to the
same value by simply programming the Left channel attenuation register. The tracking mode is enabled or
disabled using a control register bit. The tracking function is disabled by default.
The SRC includes digital de-emphasis filtering for the audio input data. The de-emphasis filter provides
normalization for 50/15
normalization for 50/15
μ
s pre-emphasized audio data. The de-emphasis filter supports 32kHz, 44.1kHz, and
48kHz input sampling rates. The filter is controlled by the DEM0, DEM1, and AUTODEM bits in control register
0x2E. The DEM0 and DEM1 bits allow the user to manually configure the de-emphasis filter operation. By
default, the de-emphasis filtering is disabled. The AUTODEM bit, when enabled, overrides the setting of the
0x2E. The DEM0 and DEM1 bits allow the user to manually configure the de-emphasis filter operation. By
default, the de-emphasis filtering is disabled. The AUTODEM bit, when enabled, overrides the setting of the
34
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