
1999 Dec 20
28
Philips Semiconductors
Product specification
Digital TV Sound Processor (DTVSP)
TDA9875A
Notes
1.
Definitions of levels and level setting:
a) The full-scale level for analog audio signals is 1.4 V (RMS).
b) The nominal level at the digital crossbar switch is defined at
15 dB (full-scale).
c) Nominal audio input levels for external and mono: 500 mV (RMS) at
9 dB (full-scale).
d) See also Tables 7 and 8.
All analog and digital supply ground pins are connected internally.
Set demodulator to AM mode. Apply an AM carrier (with 1 kHz and 100%) to one channel. Check AGC step. Switch
AGC off and set AGC to the gain step found. Measure the 1 kHz signal level of this channel and take it as a reference.
Switch to the other SIF input to which no signal is connected and which is terminated with 50
. Now measure the
1 kHz crosstalk signal level. The SIF source resistance should be low (50
).
NICAM in accordance with “EBU specification” Audio performance is limited by the dynamic range of the NICAM728
system. Due to compansion, the quantization noise is never lower than
62 dB (unweighted RMS) with respect to
the input level.
FM source; in dual mode only A (respectively B) signal modulated; measured at B (respectively A) channel output;
V
o
= 1 V (RMS) of modulated channel.
FM source; in stereo mode only L (respectively R) signal modulated; measured at R (respectively L) channel output;
V
o
= 1 V (RMS) of modulated channel. The stereo channel separation may be limited by adjustment tolerances of
the transmitter.
If the supply voltage for the TDA9875A is switched off, because of the ESD protection circuitry, all audio input pins
are short-circuited. To avoid a short-circuit at the SCART inputs a 15 k
resistor (
3 dB divider) has to be used.
The SCART specification allows a signal level of up to 2 V (RMS). Because of signal handling limitations due to the
5 V supply voltage for the TDA9875A, there is a need for fixed 3 dB attenuators at the SCART inputs. To achieve
SCART-to-SCART copies with 0 dB gain, there are 3 dB/0 dB amplifiers at the outputs of SCART 1 and SCART 2
and at the line output. The attenuator is realized by an internal resistor that works together with an external series
resistor as a voltage divider. With this voltage divider the maximum SCART input signal level of 2 V (RMS) is scaled
down to 1.4 V (RMS) at the input pin. To avoid clipping, the 3 dB gain must not be used if the SCART input signal is
larger than 1.4 V (RMS).
ADC level adjust is 6 dB, all other level adjusts are 0 dB. If an external
3 dB divider is used set output buffer gain
to 3 dB, tone control to 0 dB, AVL off and volume control to 0 dB.
2.
3.
4.
5.
6.
7.
8.
9.
X
J
X
D
X
A
adjustment tolerance
drift
ageing
±
30
±
30
±
5
10
6
10
6
across temperature range
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
year
6
–
10