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參數(shù)資料
| 型號： | LM4666SD |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | Filterless High Efficiency Stereo 1.2W Switching Audio Amplifier |
| 中文描述： | 1.2 W, 2 CHANNEL, AUDIO AMPLIFIER, DSO14 |
| 封裝： | LLP-14 |
| 文件頁數(shù)： | 13/15頁 |
| 文件大?。?/td> | 642K |
| 代理商： | LM4666SD |
Application Information
(Continued)
REFERENCE DESIGN BOARD SCHEMATIC
In addition to the minimal parts required for the application
circuit, a measurement filter is provided on the evaluation
circuit board so that conventional audio measurements can
be conveniently made without additional equipment. This is a
balanced input, grounded differential output low pass filter
with a 3dB frequency of approximately 35kHz and an on
board termination resistor of 300
(see schematic). Note
that the capacitive load elements are returned to ground.
This is not optimal for common mode rejection purposes, but
due to the independent pulse format at each output there is
a significant amount of high frequency common mode com-
ponent on the outputs. The grounded capacitive filter ele-
ments attenuate this component at the board to reduce the
high frequency CMRR requirement placed on the analysis
instruments.
Even with the grounded filter the audio signal is still differ-
ential necessitating a differential input on any analysis instru-
ment connected to it. Most lab instruments that feature BNC
connectors on their inputs are
NOT
differential responding
because the ring of the BNC is usually grounded.
The commonly used Audio Precision analyzer is differential
but its ability to accurately reject fast pulses of 160ns width is
questionable necessitating the on board measurement filter.
When the signal needs to be single-ended, use an audio
signal transformer to convert the differential output to a
single ended output. Depending on the audio transformer’s
characteristics, there may be some attenuation of the audio
signal which needs to be taken into account for correct
measurement of performance.
Measurements made at the output of the measurement filter
suffer attenuation relative to the primary, unfiltered outputs
even at audio frequencies. This is due to the resistance of
the inductors interacting with the termination resistor (300
)
and is typically about -0.35dB (4%). In other words, the
voltage levels and corresponding power levels indicated
through the measurement filter are slightly lower than those
that actually occur at the load placed on the unfiltered out-
puts. This small loss in the filter for measurement gives a
lower output power reading than what is really occurring on
the unfiltered outputs and its load.
The AUX-0025 Switching Amplifier Measurement Filter from
Audio Precision may be used instead of the on board mea-
surement filter. The AUX-0025 filter should be connected to
the high current direct outputs on the evaluation board and in
series with the measurement equipment. Attaching oscillo-
scope probes on the outputs of the AUX-0025 filter will
display the audio waveforms. The AUX-0025 filter may also
be connected to the on board filter without any adverse
effects.
20055801
FIGURE 4.
L
www.national.com
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM4666SD/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4666SDA | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Filterless High Efficiency Stereo 1.2W Switching Audio Amplifier |
| LM4666SDBD | 功能描述:音頻 IC 開發(fā)工具 LM4666SD EVAL BOARD RoHS:否 制造商:Texas Instruments 產品:Evaluation Kits 類型:Audio Amplifiers 工具用于評估:TAS5614L 工作電源電壓:12 V to 38 V |
| LM4666SDBD/NOPB | 功能描述:音頻 IC 開發(fā)工具 LM4666 Eval Brd RoHS:否 制造商:Texas Instruments 產品:Evaluation Kits 類型:Audio Amplifiers 工具用于評估:TAS5614L 工作電源電壓:12 V to 38 V |
| LM4666SDX | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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