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參數(shù)資料
| 型號： | LM4665 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 音頻放大器 |
| 英文描述： | Filterless High Efficiency 1W Switching Audio Amplifier |
| 中文描述： | 濾波1W的高效率開關(guān)音頻放大器 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大小： | 1018K |
| 代理商： | LM4665 |
Application Information
(Continued)
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 in-
strument connected to it. Most lab instruments that feature
BNC connectors on their inputs are
NOT
differential re-
sponding 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 in doubt or when the signal needs to be single-
ended, use an audio signal transformer to convert the differ-
ential output to a single ended output. Depending on the
audio transformer’s characteristics, there may be some at-
tenuation 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.
LM4665 MSOP BOARD ARTWORK
Composite View
Silk Screen
200270B2
200270B3
Top Layer
Bottom Layer
200270B4
200270B5
L
www.national.com
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| LM4665ITLX | Filterless High Efficiency 1W Switching Audio Amplifier |
| LM4665LD | Filterless High Efficiency 1W Switching Audio Amplifier |
| LM4665MM | Filterless High Efficiency 1W Switching Audio Amplifier |
| LM4665ITL | Filterless High Efficiency 1W Switching Audio Amplifier |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4665 WAF | 制造商:Texas Instruments 功能描述: |
| LM4665B WAF | 制造商:Texas Instruments 功能描述: |
| LM4665ITL | 制造商:Texas Instruments 功能描述:Audio Amp Speaker 1-CH Mono 1.4W Class-AB 9-Pin uSMD T/R 制造商:Texas Instruments 功能描述:1W Class D Switching Amplifier,LM4665ITL |
| LM4665ITL/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4665ITLX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Filterless High Efficiency 1W Switching Audio Amplifier |
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