參數(shù)資料
型號: 93526374518
廠商: NXP SEMICONDUCTORS
元件分類: 接收器
英文描述: FM, AUDIO DEMODULATOR, PQFP44
封裝: PLASTIC, SOT-205, QFP-44
文件頁數(shù): 4/71頁
文件大?。?/td> 269K
代理商: 93526374518
2000 Aug 04
12
Philips Semiconductors
Product specication
Digital TV sound demodulator/decoder
TDA9874A
6.2.4
FM (AM) PATH
A high-pass filter suppresses DC offsets from the
FM demodulator that may occur due to carrier frequency
offsets, and supplies the FM monitor function with DC
values, e.g. for the purpose of microprocessor controlled
carrier search or fine tuning functions.
An adaptive de-emphasis is available for
Wegener-Panda 1 encoded satellite programs.
The de-emphasis stage offers a choice of settings for the
supported TV standards.
The 2-channel decoder performs the dematrixing of
1
2(L + R), R to L and R signals of 12(L + R) and 12(L R)
to L and R signals or of channel 1 and channel 2 to
L and R signals, as demanded by the different TV
standards or user preferences.
Automatic FM dematrixing is also supported.
Using the high deviation mode, only channel 1 (mono) can
be demodulated. The scaling is
6 dB compared to
2-channel decoding.
6.2.5
MONITOR
This function provides data words from the
FM demodulator outputs and FM and NICAM signals for
external use, such as carrier search or fine tuning.
The peak level of these signals can also be observed.
Source selection and data read out are performed via the
I2C-bus.
6.2.6
DIGITAL CROSSBAR SWITCH
The input channels are derived from the FM and NICAM
paths, while the output channels comprise I2S-bus and the
audio DACs to the analog crossbar switch. It should be
noted that there is no connection from the external analog
audio inputs to the digital crossbar switch.
6.2.7
DIGITAL AUDIO OUTPUT
The digital audio output interface comprises an I2S-bus
output port and a system clock output. The I2S-bus port is
equipped with a level adjustment facility that can change
the signal level in a
±15 dB range in 1 dB steps. Muting is
possible, too, and outputs can be disabled to improve EMC
performance.
The I2S-bus output matrix provides the functions for forced
mono, stereo, channel swap, channel 1 or channel 2.
Automatic selection for TV applications is possible. In this
case the microcontroller program only has to provide a
user controlled sound A or sound B selection.
6.2.8
STEREO CHANNEL TO THE ANALOG CROSSBAR PATH
A level adjustment function is provided with control
positions of 0 dB, +3 dB, +6 dB and +9 dB in combination
with the audio DACs. The Automatic Volume Level (AVL)
function provides a constant output level of
20 dB (full-scale) for input levels between
0 dB (full-scale) and
26 dB (full-scale). There are some
xed decay time constants to choose from, i.e.
2, 4 or 8 seconds.
Automatic selection for TV applications is possible. In this
case the microcontroller program only has to provide a
user controlled sound A or sound B selection.
6.2.9
GENERAL
The level adjustment functions can provide signal gain at
multiple locations. Great care has to be taken when using
gain with large input signals, e.g., due to overmodulation,
in order not to exceed the maximum possible signal swing,
which would cause severe signal distortion. The nominal
signal level of the various signal sources to the digital
crossbar switch should be 15 dB below digital full-scale
(
15 dB full-scale).
相關(guān)PDF資料
PDF描述
93526374557 FM, AUDIO DEMODULATOR, PQFP44
935263897551 1-CH 10-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQFP32
935263898112 1-CH 10-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PDSO28
935263897518 1-CH 10-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PQFP32
935263898118 1-CH 10-BIT PROPRIETARY METHOD ADC, PARALLEL ACCESS, PDSO28
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
935264217557 制造商:NXP Semiconductors 功能描述:SUB ONLY IC
935267356112 制造商:NXP Semiconductors 功能描述:IC TEA1507PN
935268081112 制造商:NXP Semiconductors 功能描述:SUB ONLY IC
935268721125 制造商:NXP Semiconductors 功能描述:Buffer/Line Driver 1-CH Non-Inverting 3-ST CMOS 5-Pin TSSOP T/R
935269304128 制造商:ST-Ericsson 功能描述:IC AUDIO CODEC W/TCH SCRN 48LQFP