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| 型号： | TDA9884HN |
| 厂商： | NXP SEMICONDUCTORS |
| 元件分类： | 接收器 |
| 英文描述： | AM/FM, AUDIO/VIDEO DEMODULATOR, PQCC32 |
| 封装： | 5 X 5 MM, 0.85 MM HEIGHT, PLASTIC, MO-220, HVQFN-32 |
| 文件页数： | 3/58页 |
| 文件大小： | 290K |
| 代理商： | TDA9884HN |
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TDA9884_2
Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet
Rev. 02 — 12 May 2006
11 of 58
Philips Semiconductors
TDA9884
I2C-bus controlled multistandard alignment-free IF-PLL
7.10 SIF-AGC detector
SIF gain control is performed by the detection of the DC component of the
AM demodulator output signal. This DC signal corresponds directly to the SIF voltage at
the output of the SIF amplier so that a constant SIF signal is supplied to the
AM demodulator and to the single reference QSS mixer.
By switching the gain of the input amplier of the SIF-AGC detector via the I2C-bus, the
internal SIF level for FM sound is 5.5 dB lower than for AM sound. This is to adapt the
SIF-AGC characteristic to the VIF-AGC characteristic. The adaption is ideal for a
picture-to-sound FM carrier ratio of 13 dB.
Via a comparator, the integrated AGC capacitor is charged or discharged for the
generation of the required SIF gain. Due to AM sound, the AGC reaction time is slow
(fc < 20 Hz for the closed AGC loop). For reducing this AM sound time constant in the
event of a decreasing IF amplitude step, the charging and discharging currents of the
AGC capacitor are increased by a factor of 12 (fast mode) when the VIF-AGC detector (at
positive modulation mode) operates in the fast mode too. An additional circuit (threshold
approximately 7 dB) ensures a very fast gain reduction for a large increasing IF amplitude
step.
For negative modulation and QSS mode the AGC also is set to fast mode. For negative
modulation and mobile mode the currents are increased additionally by a factor of 36.
7.11 Single reference QSS mixer
With the present system a high performance Hi-Fi stereo sound processing can be
achieved. For a simplied application without a SIF SAW lter, the single reference QSS
mixer can be switched to the intercarrier mode via the I2C-bus.
The single reference QSS mixer generates the 2nd FM TV sound intercarrier signal. It is
realized by a linear multiplier which multiplies the SIF amplier output signal and the
VIF-PLL VCO signal (90 degrees output) which is locked to the picture carrier. In this way
the QSS mixer operates as a quadrature mixer in the intercarrier mode and provides
suppression of the low frequency video signals.
In the true split sound mode the VIF-PLL VCO is locked by a synthesizer. By this the 2nd
FM TV sound intercarrier signal is generated independently from the vision carrier so that
in the case of a low RF level, the sound demodulation is possible where the VIF-PLL
would unlock. In the true split sound mode the VIF demodulation is not available.
The QSS mixer output signal is fed internally via a high-pass and low-pass combination to
the FM demodulator as well as via an operational amplier to the intercarrier output
pin SIOMAD.
7.12 AM demodulator
The amplitude modulated SIF amplier output signal is fed both to a two-stage limiting
amplier that removes the AM and to a linear multiplier. The result of the multiplication of
the SIF signal with the limiter output signal is AM demodulation (passive synchronous
demodulator). The demodulator output signal is fed via a low-pass lter that attenuates
the carrier harmonics and via the input amplier of the SIF-AGC detector to the audio
amplier.
相关PDF资料 |
PDF描述 |
|---|---|
| TDA9885HN/V5 | AM/FM, AUDIO/VIDEO DEMODULATOR, PQCC32 |
| TDA9885T/V5 | AM/FM, AUDIO/VIDEO DEMODULATOR, PDSO24 |
| TDA9885TS/V5 | AM/FM, AUDIO/VIDEO DEMODULATOR, PDSO24 |
| TDA9886HN/V5 | AM/FM, AUDIO/VIDEO DEMODULATOR, PQCC32 |
| TDA9886T/V5 | AM/FM, AUDIO/VIDEO DEMODULATOR, PDSO24 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| TDA9884TS | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:I2C-bus controlled multistandard alignment-free IF-PLL for mobile reception |
| TDA9884TS/V1 | 功能描述:调节器/解调器 MOBILE VIF AND SIF DEMODULATOR RoHS:否 制造商:Texas Instruments 封装 / 箱体:PVQFN-N24 封装:Reel |
| TDA9884TS/V1,112 | 功能描述:调节器/解调器 MOBILE VIF AND SIF RoHS:否 制造商:Texas Instruments 封装 / 箱体:PVQFN-N24 封装:Reel |
| TDA9884TS/V1,118 | 功能描述:调节器/解调器 MOBILE VIF AND SIF RoHS:否 制造商:Texas Instruments 封装 / 箱体:PVQFN-N24 封装:Reel |
| TDA9884TS/V1/S1,11 | 功能描述:调节器/解调器 MOBILE VIF AND SIF RoHS:否 制造商:Texas Instruments 封装 / 箱体:PVQFN-N24 封装:Reel |
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