
August 1994
5
Philips Semiconductors
Product specification
Quadruple filter DAC
TDA1314T
Fig.2 Pin configuration.
FUNCTIONAL DESCRIPTION
I
2
S-bus interface
The word select input (pin 26) is connected to the word
select line of the I
2
S-bus interface. This interface has
a standard I
2
S-bus specification as described in the
Philips
“I
2
S-bus specification”
(ordering number
9398 332 10011). Figure 4 shows an excerpt of the Philips
I
2
S-bus specification interface report with respect to the
general timing and format of the I
2
S-bus. WS logic 0
means left channel word, logic 1 means right
channel word.
The serial clock input (pin 4) must be in accordance with
the I
2
S-bus specification, i.e. a continuous clock.
Serial data front (SDF, pin 25) and serial data rear (SDR,
pin 24) are the I
2
S-bus serial data lines to be processed in
the DACs for the loudspeakers of the car (see Fig.2, blocks
DACFL and DACFR for the front loudspeakers and blocks
DACRL and DACRR for the right loudspeakers). FL stands
for Front Left, FR for Front Right, RL for Rear Left and RR
for Rear Right. In order to utilize the capabilities of this IC
fully, the data word length should be 18 bits. Signals
derived from this block are 4
×
18-bit parallel data words
which are applied to the 4f
s
up-sample filters.
4ASF generator
S
YNTHESIZER
SELINPH (pin 3) and WS (pin 26) are the data inputs for
this block which generates the FASFDAC, this being the
4f
as
signal (at 4 times the audio sample frequency), which
is used to latch the data words to the DACs and as a
reference to the clock generator block for the up-sample
filters. It consists of a digital PLL operating at the master
clock signal MCLK (pin 5). In normal mode (i.e. in the
event that the MCLK signal on pin 5 is a jitter free clock,
with a frequency of integer multiples between 45 and 128,
of 4 times the frequency of the WS signal) this block is able
to generate a jitter free FASFDAC signal for optimum
performance of the DAC. This mode is called the free
running mode.
If, in some applications, there is considerable jitter on the
MCLK while WS is more stable (less jitter), the
phase-locked mode should be selected. This mode is
normally not used and is not recommended.