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參數(shù)資料
| 型號： | TDA9874APS |
| 廠商： | NXP SEMICONDUCTORS |
| 元件分類： | 接收器 |
| 英文描述： | Digital TV sound demodulator/decoder |
| 中文描述： | AM/FM, AUDIO DEMODULATOR, PDIP42 |
| 封裝： | 0.600 INCH, SHRINK, PLASTIC, MS-020, SOT-270-1, DIP-42 |
| 文件頁數(shù)： | 11/68頁 |
| 文件大?。?/td> | 231K |
| 代理商： | TDA9874APS |
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1999 Dec 03
11
Philips Semiconductors
Preliminary specification
Digital TV sound demodulator/decoder
TDA9874A
6.1.10
C
RYSTAL OSCILLATOR
The digital controlled crystal oscillator (DCXO) is fully
integrated. Only an external 24.576 MHz crystal is
required.
6.1.11
T
EST PINS
All test pins are active HIGH. In normal operation of the
device they can be left open-circuit, as they have internal
pull-down resistors. Test functions are for manufacturing
tests only and are not available to customers.
6.1.12
P
OWER FAIL DETECTOR
The power fail detector monitors the internal power supply
for the digital part of the device. If the supply has
temporarily been lower than the specified lower limit, the
power failure register bit PFR in subaddress 0 (see
Section 10.4.1), will be set to HIGH. The CLRPFR bit,
slave register subaddress 1 (see Section 10.3.3), resets
the Power-on reset flip-flop to LOW. If this is detected, an
initialization of the TDA9874A has to be performed to
ensure reliable operation.
6.1.13
P
OWER
-
ON RESET
The reset is active LOW. In order to perform a reset at
power-up, a simple RC circuit may be used which consists
of an integrated passive pull-up resistor and an external
capacitor connected to ground. The pull-up resistor has a
nominal value of 50 k
, which can easily be measured
between pins CRESET and V
DDD3
. Before the supply
voltage has reached a certain minimum level, the state of
the circuit is completely undefined and remains in this
undefined state until a reset is applied.
The reset is guaranteed to be active when:
The power supply is within the specified limits
(4.5 to 5.5 V)
The crystal oscillator (DCXO) is functioning
The voltage at pin CRESET is below 0.3V
DDD
(1.5 V if
V
DDD
= 5.0 V, typically below 1.8 V).
The required capacitor value depends on the gradient of
the rising power supply voltage. The time constant of the
RC circuit should be clearly larger than the rise time of the
power supply [to make sure that the reset condition is
always satisfied (see Fig.4)], even when considering
tolerance spreading. To avoid problems with a too slow
discharging of the capacitor at power-down, it may be
helpful to add a diode from the CRESET pin to V
DDD
.
It should be noted that the internal ESD protection diode
does not help here as it only conducts at higher voltages.
Under difficult power supply conditions (e.g. very slow or
non-monotonic ramp-up), it is recommended to drive the
reset line from a microcontroller port or the like.
6.2
Description of the DSP
6.2.1
L
EVEL SCALING
All input channels to the digital crossbar switch are
equipped with a level adjustment facility to change the
signal level in a range of
±
15 dB. Adjusting the signal level
is intended to compensate for the different modulation
parameters of the various TV standards. Under nominal
conditions it is recommended to scale all input channels to
be 15 dB below full-scale [
15 dB (FS)]. This will create
sufficient headroom to cope with overmodulation and
avoids changes of the volume impression when switching
from FM to NICAM or vice versa.
6.2.2
NICAM
PATH
The NICAM path has a switchable J17 de-emphasis.
6.2.3
NICAM
AUTO
-
MUTE
If NICAM is received, the auto-mute is enabled and the
signal quality becomes poor. The digital crossbar switches
automatically to FM, channel 1 or the analog mono input,
as selected by bit AMSEL. This automatic switching
depends on the NICAM bit error rate. The auto-mute
function can be disabled via the I
2
C-bus.
handbook, halfpage
MHB587
reset active
guaranteed
1.5
5
t
VCRESET
<
0.3VDDD
VDDD
>
4.5 V
Fig.4 Reset at power-on.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TDA9874H | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital TV sound demodulator/decoder |
| TDA9875 | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital TV Sound Processor DTVSP |
| TDA9875A | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital TV Sound Processor DTVSP |
| TDA9875AH | 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Digital TV Sound Processor DTVSP |
| TDA9875AH/V2,557 | 功能描述:IC SOUND PROC DGTL TV 64QFP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻處理 系列:- 其它有關(guān)文件:STA321 View All Specifications 標(biāo)準(zhǔn)包裝:1 系列:Sound Terminal™ 類型:音頻處理器 應(yīng)用:數(shù)字音頻 安裝類型:表面貼裝 封裝/外殼:64-LQFP 裸露焊盤 供應(yīng)商設(shè)備封裝:64-LQFP EP（10x10） 包裝:Digi-Reel® 其它名稱:497-11050-6 |
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