SRC4190_14 Datasheet, PDF (15/29 Pages) Texas Instruments – 192kHz Stereo Asynchronous Sample Rate Converters

PRODUCT OVERVIEW
The SRC4190 is an asynchronous sample rate converter
(ASRC) designed for professional audio applications. Opera-
tion at input and output sampling frequencies up to 212kHz
is supported, with an input/output sampling ratio range of
16:1 to 1:16. Excellent dynamic range and Total Harmonic
Distortion + Noise (THD+N) are achieved by employing high
performance and linear phase digital filtering. Digital filtering
options allow for lower group delay processing.
The audio input and output ports support standard audio data
formats, as well as a TDM interface mode. Word lengths of
24-, 20-, 18-, and 16-bits are supported. Both ports may
operate in Slave mode, deriving their word and bit clocks
from external input and output devices. Alternatively, one
port may operate in Master mode while the other remains in
Slave mode. In Master mode, the LRCK and BCK clocks are
derived from the reference clock input, RCKI. The flexible
configuration of the input and output ports allows connection
to a wide variety of audio data converters, interface devices,
digital signal processors, and programmable logic.
A bypass mode is included, which allows audio data to be
passed directly from the input port to the output port, bypass-
ing the ASRC function. The bypass option is useful for
passing through encoded or compressed audio data, or non-
audio control or status data.
A soft mute function is available providing artifact-free opera-
tion while muting the audio output signal. The mute attenu-
ation is typically –128dB.
FUNCTIONAL BLOCK DIAGRAM
Figure 1 shows a functional block diagram of the SRC4190.
Audio data is received at the input port, clocked by either the
audio data source in Slave mode or by the SRC4190 in
Master mode. The output port data is clocked by either the
audio data source in Slave mode, or by the SRC4190 in
Master mode. The input data is passed through interpolation
filters which up-sample the data, which is then passed on to
the re-sampler. The rate estimator compares the input and
output sampling frequencies by comparing LRCKI, LRCKO,
and a reference clock. The results include an offset for the
FIFO pointer and the coefficients needed for re-sampling
function.
The output of the re-sampler is then passed on to the
decimation filter. The decimation filter performs down-sam-
pling and anti-alias filtering functions.
LRCKI
BCKI
SDIN
MODE [2:0]
IFMT [2:0]
OFMT [1:0]
OWL [1:0]
MUTE
BYPAS
LGRP
RST
LRCKO
BCKO
SDOUT
TDMI
RCKI
Audio
Input
Port
f_SIN
Interpolation
16f_SIN
16f_SOUT
Filters
Re-Sampler
Control
Logic
Audio
Output
Port
Reference
Clock
LRCKI
REFCLK
Rate
Estimator
LRCKO
RDY
REFCLK
f_SOUT
Decimation
Filters
Power
V_DD
DGND
V_IO
DGND
FIGURE 1. SRC4190 Functional Block Diagram.
SRC4190
15
SBFS023B
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