- 您現(xiàn)在的位置：買(mǎi)賣(mài)IC網(wǎng) > PDF目錄98195 > TDA7400D (STMICROELECTRONICS) SPECIALTY CONSUMER CIRCUIT, PDSO28 PDF資料下載
參數(shù)資料
| 型號(hào)： | TDA7400D |
| 廠商： | STMICROELECTRONICS |
| 元件分類(lèi)： | 消費(fèi)家電 |
| 英文描述： | SPECIALTY CONSUMER CIRCUIT, PDSO28 |
| 封裝： | SOP-28 |
| 文件頁(yè)數(shù)： | 10/28頁(yè) |
| 文件大?。?/td> | 277K |
| 代理商： | TDA7400D |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)第8頁(yè)第9頁(yè)當(dāng)前第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)第16頁(yè)第17頁(yè)第18頁(yè)第19頁(yè)第20頁(yè)第21頁(yè)第22頁(yè)第23頁(yè)第24頁(yè)第25頁(yè)第26頁(yè)第27頁(yè)第28頁(yè)
supplied by his own biasing circuit.
Trigger Path
The incoming MPX signal is highpass filtered,
amplified and rectified. This second order high-
pass-filter has a corner frequency of 140kHz.
The rectified signal, RECT, is lowpass filtered to
generate a signal called PEAK. Also noise with a
frequency 140kHz increases the PEAK voltage.
The resulting voltage can be adjusted by use of
the noise rectifier discharge current.
The PEAK voltage is fed to a threshold generator,
which adds to the PEAK voltage a DC depend-
ent threshold VTH. Both signals, RECT and
PEAK+VTH are fed to a comparator which trig-
gers a re-triggerable monoflop. The monoflop’s
output activates the sample-and-hold circuits in
the signalpath for selected duration.
Automatic Noise Controlled Threshold Adjust-
ment (ATC)
There are mainly two independent possibilities for
programming the trigger threshold:
a the low threshold in 8 steps (bits D0 to D2 of
the noiseblanker byte)
b the noise adjusted threshold in 4 steps
(bits D3 and D4 of the noiseblanker byte,
see fig. 14).
The low threshold is active in combination with a
good MPX signal without any noise; the PEAK
voltage is less than 1V. The sensitivity in this op-
eration is high.
If the MPX signal is noisy the PEAK voltage in-
creases due to the higher noise, which is also
rectified. With increasing of the PEAK voltage the
trigger threshold increases, too.
This particular
gain is programmable in 4 steps (see fig. ...).
AUTOMATIC THRESHOLD CONTROL MECHA-
NISM
Automatic
Threshold
Control
by
the
Stereoblend Voltage
Besides the noise controlled threshold adjust-
ment there is an additional possibility for influenc-
ing the trigger threshold. It is depending on the
stereoblend control.
The point where the MPX signal starts to become
noisy is fixed by the RF part. Therefore also the
starting point of the normal noise-controlled trig-
ger adjustment is fixed (fig. 11). In some cases
the behaviour of the noiseblanker can be im-
proved by increasing the threshold even in a re-
gion of higher fieldstrength. Sometimes a wrong
triggering occures for the MPX signal often shows
distortion in this range which can be avoided
even if using a low threshold.
Because of the overlap of this range and the
range of the stereo/mono transition it can be con-
trolled by stereoblend. This threshold increase is
programmable in 3 steps or switched off with bits
D0 and D1 of the fieldstrength control byte.
Over Deviation Detector
If the system is tuned to stations with a high de-
viation the noiseblanker can trigger on the higher
frequencies of the modulation. To avoid this
wrong behaviour, which causes noise in the out-
put signal, the noiseblanker offers a deviation de-
pendent threshold adjustment.
+
-
RECTIFIER
LOWPASS
RECT
+
THRESHOLD
GENERATOR
VTH
PEAK
ADDITIONAL
THRESHOLD
CONTROL
MONOFLOP
HOLDN
MPX
D98AU856
MPX
CONTROL
Figure 17. Block Diagram of the Noiseblanker
TDA7400D
18/28
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TDA7400 | SPECIALTY CONSUMER CIRCUIT, PQFP44 |
| TDA7402TR | SPECIALTY CONSUMER CIRCUIT, PQFP44 |
| TDA7402 | SPECIALTY CONSUMER CIRCUIT, PQFP44 |
| TDA7403D | SPECIALTY CONSUMER CIRCUIT, PDSO20 |
| TDA7403DTR | SPECIALTY CONSUMER CIRCUIT, PDSO20 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TDA7400DTR | 功能描述:音頻 DSP ADV CAR SGNL PROCESR RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
| TDA7401 | 功能描述:音頻 DSP Digital Audio Proc RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
| TDA7401013TR | 功能描述:音頻 DSP Digital Audio Proc RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
| TDA7401D | 功能描述:音頻 DSP Digital Audio Proc RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
| TDA7402 | 功能描述:音頻 DSP Car Radio Signal RoHS:否 制造商:Texas Instruments 工作電源電壓: 電源電流: 工作溫度范圍: 安裝風(fēng)格: 封裝 / 箱體: 封裝:Tube |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。