- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄98195 > TDA7402 (STMICROELECTRONICS) SPECIALTY CONSUMER CIRCUIT, PQFP44 PDF資料下載
參數(shù)資料
| 型號： | TDA7402 |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 消費家電 |
| 英文描述： | SPECIALTY CONSUMER CIRCUIT, PQFP44 |
| 封裝： | 10 X 10 MM, 1.40 MM HEIGHT, TQFP-44 |
| 文件頁數(shù)： | 38/69頁 |
| 文件大小： | 865K |
| 代理商： | TDA7402 |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁第36頁第37頁當(dāng)前第38頁第39頁第40頁第41頁第42頁第43頁第44頁第45頁第46頁第47頁第48頁第49頁第50頁第51頁第52頁第53頁第54頁第55頁第56頁第57頁第58頁第59頁第60頁第61頁第62頁第63頁第64頁第65頁第66頁第67頁第68頁第69頁
TDA7402
Functional description of the noise blanker
6
Functional description of the noise blanker
In the automotive environment the MPX-signal as well as the AM signal is disturbed by
spikes produced by the ignition and other radiating sources like the wiper motor. The aim of
the noiseblanker part is to cancel the audible influence of the spikes. Therefore the output of
the stereo decoder is held at the actual voltage for a time between 22 and 38s in FM (370
and 645s in AM mode). The block diagram of the noise blanker is given in Figure 34.
Figure 34.
Block diagram of the noise blanker
In a first stage the spikes must be detected but to avoid a wrong triggering on high
frequency (white) noise a complex trigger control is implemented. Behind the trigger stage a
pulse former generates the "blanking"pulse.
6.1
Trigger path FM
The incoming MPX signal is highpass-filtered, amplified and rectified. This second order
highpass filter has a corner-frequency of 140kHz. The rectified signal, RECT, is integrated
(lowpass filtered) to generate a signal called PEAK. The DC-charge/discharge behavior can
be adjusted as well as the transient behavior (MP discharge control). Also noise with a
frequency 140kHz increases the PEAK voltage. The PEAK voltage is fed to a threshold
generator, which adds to the PEAK voltage a DC dependent threshold VTH. Both signals,
RECT and PEAK+VTH are fed to a comparator which triggers a re-triggerable monoflop.
The monoflop's output activates the sample and hold circuits in the signalpath for the
selected duration.
6.2
Noise controlled threshold adjustment (NCT)
There are mainly two independent possibilities for programming the trigger threshold:
1.
the low threshold in 8 steps (bits D1 to D3 of the noiseblanker byte I)
2.
and the noise adjusted threshold in 4 steps (bits D4 and D5 of the noiseblanker byte I,
see Figure 21).
The low threshold is active in combination with a good MPX signal without noise; the PEAK
voltage is less than 1V. The sensitivity in this operation is high.
If the MPX signal is noisy (low fieldstrength) the PEAK voltage increases due to the higher
noise, which is also rectified. With increasing of the PEAK voltage the trigger threshold
increases, too. This gain is programmable in 4 steps (see Figure 25).
+
-
RECTIFIER
AM/FM
INTEGRATOR
DISCHARGE
CONTROL
FM: 22 to 40
μs
AM: 370 to 6400
μs
RECT
+
THRESHOLD
GENERATOR
VTH
PEAK
ADDITIONAL
THRESHOLD
CONTROL
MONOFLOP
HOLDN
AMIF
D00AU1132
RECTIFIER +
14-56KHz LPF
(1st. order)
140KHz HPF
(1st. order)
140KHz HPF
(2nd. order)
MPX
MPOUT
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TDA7403D | SPECIALTY CONSUMER CIRCUIT, PDSO20 |
| TDA7403DTR | SPECIALTY CONSUMER CIRCUIT, PDSO20 |
| TDA7404DTR | 1 CHANNEL(S), TONE CONTROL CIRCUIT, PDSO28 |
| TDA7404D | 1 CHANNEL(S), TONE CONTROL CIRCUIT, PDSO28 |
| TDA7405TR | SPECIALTY CONSUMER CIRCUIT, PQFP44 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TDA7402_07 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Car radio signal processor |
| TDA7402TR | 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 |
| TDA7403 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:BASIC SIGNAL PROCESSOR |
| TDA7403_02 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:BASIC SIGNAL PROCESSOR |
| TDA7403D | 功能描述:音頻 DSP Basic Signal Process 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，3分鐘左右您將得到回復(fù)。