TDA1315H/N2 データシートの表示（PDF） - Philips Electronics
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TDA1315H/N2 Datasheet PDF : 36 Pages
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Philips Semiconductors
Digital audio input/output circuit (DAIO)
Product specification
TDA1315H
BIPHASE DEMODULATOR
In the biphase modulator section, audio and non-audio
data are combined into subframes, frames and blocks, and
encoded in the biphase-mark format during transmit mode.
Although there are always 24 audio bits per sample in a
subframe, the number of significant bits can be selected as
16, 18, 20 or 24 via the control register (host mode).
AUDIO SECTION
In the audio section, the left and right channel audio
samples are taken from the demodulated data frames and
are output serially in accordance with the I2S-bus format
(for details see Chapter “References”[3] pins SD, SCK and
WS) when the TDA1315H is in the receive mode (I2S-bus
transmitter). The audio output signals are concealed or
muted in case certain errors were detected during
reception. Mute can be enforced by pin MUTE or via the
control register (host mode) and affects, depending on the
receive/transmit mode, the I2S-bus or IEC output signals.
MUTE is internally synchronized with the audio data. In the
transmit mode, there is an additional I2S-bus data input
SDAUX made available to accept audio data from, for
example, an ADC. This input can be selected either by pin
I2SSEL, by the control register or both. The I2S-bus Port
can be enabled/disabled by pin I2SOEN, by the control
register or both. In the transmit mode, I2S-bus data and
timing are supplied by an external source, the TDA1315H
then becomes an I2S-bus receiver. In this event, selection
of an I2S-bus source determines which signal is to be
output at IECO. Although the phase relationship between
system clock (SYSCLKI) and I2S timing (SCK) is not
critical they must be synchronous with each other, i.e. be
derived from the same source.
Receive mode
The IEC subframe format defines 20 bits for an audio
sample, plus 4 auxiliary bits, which can be used to extend
the word length. By default, all 24 data bits per sample are
output via the I2S-bus Port. This can be changed,
however, to 16, 18 or 20 bits via bits 2 and 3 in byte 1 of
the control register. The remaining bits will then be zero.
The serial audio clock frequency at pin SCK is 64 × fs, i.e.
there are 32 clock pulses per audio sample (left or right
channel).
Apart from detecting the out-of-lock condition of the PLL,
received data is checked for the errors listed below. All
detected errors will be flagged in the status register and
two of them brought out to a pin. Depending on the type of
error, different measures are taken.
• Validity flag set. This error condition is also output at pin
INVALID, simultaneously with the data. The
corresponding audio sample is not modified.
• Parity check error. A concealment operation is
performed on both audio channels (left and right), i.e.
the last correctly received stereo sample is output again.
• Biphase violation (other than preambles). A
concealment operation (hold) is performed on both
audio channels (left and right), i.e. the last correctly
received stereo sample is output again.
• PLL is out-of-lock. This error condition is also output at
pin UNLOCK. Both audio output channels (left and right)
are set to zero (mute). The error condition is sampled
with the HIGH-to-LOW transition of WS, i.e. muting
becomes effective when the outputting of a stereo
sample begins. When the PLL has locked again, muting
is released only after a full block of audio samples has
been received, free of errors.The INVALID output will
always be set to LOW simultaneously with this muting.
In the receive mode it is possible to select the auxiliary
I2S-bus data input SDAUX for output at pin SD. However,
there will be no suitable system clock available in the event
of an open IEC input or a disabled IEC source and output
SD will be muted when the TDA1315H is not in lock.
Regardless of which source is selected, a MUTE
command will always mute the output signal at pin SD and
set the INVALID output to LOW regardless of the validity
bit value. When mute command is disabled, muting will be
released when the outputting of the next stereo sample
begins.
1995 Jul 17
8
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