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参数资料
| 型号： | TDA9874APS/V2 |
| 厂商： | NXP SEMICONDUCTORS |
| 元件分类： | 接收器 |
| 英文描述： | AM/FM, AUDIO DEMODULATOR, PDIP42 |
| 封装： | 0.600 INCH, PLASTIC, SDIP-42 |
| 文件页数： | 3/71页 |
| 文件大小： | 304K |
| 代理商： | TDA9874APS/V2 |
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2000 Aug 04
11
Philips Semiconductors
Product specication
Digital TV sound demodulator/decoder
TDA9874A
6.1.10
CRYSTAL OSCILLATOR
The digital controlled crystal oscillator (DCXO) is fully
integrated. Only an external 24.576 MHz crystal is
required.
6.1.11
TEST 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
POWER 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 7.4.1), will be set to logic 1. Bit CLRPFR, slave
register subaddress 1 (see Section 7.3.3), resets the
Power-on reset flip-flop to logic 0. If this is detected, an
initialization of the TDA9874A has to be performed to
ensure reliable operation.
6.1.13
POWER-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 VDDD3. 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 0.3VDDD (1.5 V if
VDDD = 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 pin CRESET to VDDD.
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
LEVEL 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. 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 I2C-bus.
handbook, halfpage
MHB587
reset active
guaranteed
1.5
5
V
t
VCRESET < 0.3VDDD
VDDD > 4.5 V
Fig.4 Reset at Power-on.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TDA9874H | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Digital TV sound demodulator/decoder |
| TDA9875 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Digital TV Sound Processor DTVSP |
| TDA9875A | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:Digital TV Sound Processor DTVSP |
| TDA9875AH | 制造商:PHILIPS 制造商全称: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 类别:集成电路 (IC) >> 线性 - 音频处理 系列:- 其它有关文件:STA321 View All Specifications 标准包装:1 系列:Sound Terminal™ 类型:音频处理器 应用:数字音频 安装类型:表面贴装 封装/外壳:64-LQFP 裸露焊盘 供应商设备封装:64-LQFP EP（10x10） 包装:Digi-Reel® 其它名称:497-11050-6 |
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