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參數(shù)資料
| 型號： | LM4671 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 音頻放大器 |
| 英文描述： | Filterless High Efficiency 2.5W Switching Audio Amplifier |
| 中文描述： | 濾波2.5W的高效率開關音頻放大器 |
| 文件頁數(shù)： | 12/18頁 |
| 文件大?。?/td> | 969K |
| 代理商： | LM4671 |
Application Information
(Continued)
the LM4671 is 0V. Input capacitors create a high-pass filter
with the input resistors, R
i
. The –3dB point of the high-pass
filter is found using Equation (3) below.
f
C
= 1 / (2
π
R
i
C
i
) (Hz)
(3)
The input capacitors may also be used to remove low audio
frequencies. Small speakers cannot reproduce low bass
frequencies so filtering may be desired . When the LM4671
is using a single-ended source, power supply noise on the
ground is seen as an input signal by the +IN input pin that is
capacitor coupled to ground (See Figures 5 – 7). Setting the
high-pass filter point above the power supply noise frequen-
cies, 217Hz in a GSM phone, for example, will filter out this
noise so it is not amplified and heard on the output. Capaci-
tors with a tolerance of 10% or better are recommended for
impedance matching.
DIFFERENTIAL CIRCUIT CONFIGURATIONS
The LM4671 can be used in many different circuit configu-
rations. The simplest and best performing is the DC coupled,
differential input configuration shown in Figure 2. Equation
(2) above is used to determine the value of the R
i
resistors
for a desired gain.
Input capacitors can be used in a differential configuration as
shown in Figure 3. Equation (3) above is used to determine
the value of the C
i
capacitors for a desired frequency re-
sponse due to the high-pass filter created by C
i
and R
i
.
Equation (2) above is used to determine the value of the R
i
resistors for a desired gain
The LM4671 can be used to amplify more than one audio
source. Figure 4 shows a dual differential input configuration.
The gain for each input can be independently set for maxi-
mum design flexibility using the R
resistors for each input
and Equation (2). Input capacitors can be used with one or
more sources as well to have different frequency responses
depending on the source or if a DC voltage needs to be
blocked from a source.
SINGLE-ENDED CIRCUIT CONFIGURATIONS
The LM4671 can also be used with single-ended sources but
input capacitors will be needed to block any DC at the input
terminals. Figure 5 shows the typical single-ended applica-
tion configuration. The equations for Gain, Equation (2), and
frequency response, Equation (3), hold for the single-ended
configuration as shown in Figure 5.
When using more than one single-ended source as shown in
Figure 6, the impedance seen from each input terminal
should be equal. To find the correct values for C
and R
i3
connected to the +IN input pin the equivalent impedance of
all the single-ended sources are calculated. The single-
ended sources are in parallel to each other. The equivalent
capacitor and resistor, C
and R
i3
, are found by calculating
the parallel combination of all C
values and then all R
val-
ues. Equations (4) and (5) below are for any number of
single-ended sources.
C
i3
= C
i1
+ C
i2
+ C
in
... (μF)
(4)
R
i3
= 1 / (1/R
i1
+ 1/R
i2
+ 1/R
in
...) (
)
(5)
The LM4671 may also use a combination of single-ended
and differential sources.Atypical application with one single-
ended source and one differential source is shown in Figure
7. Using the principle of superposition, the external compo-
nent values can be determined with the above equations
corresponding to the configuration.
201073I7
FIGURE 2. Differential input configuration
L
www.national.com
12
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM4671_07 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Filterless High Efficiency 2.5W Switching Audio Amplifier |
| LM4671_08 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Filterless High Efficiency 2.5W Switching Audio Amplifier |
| LM4671ITL | 制造商:Texas Instruments 功能描述:Audio Amp Speaker 1-CH Mono 2.5W Class-AB 9-Pin uSMD T/R 制造商:Texas Instruments 功能描述:IC AMP FILTERLESS 2.5W SMD 4671 |
| LM4671ITL/NOPB | 功能描述:音頻放大器 Filterless Hi Eff 2.5W Swtch Audio Amp 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 |
| LM4671ITLBD | 功能描述:BOARD EVALUATION LM4671ITL RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 音頻放大器 系列:Boomer® 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1 系列:- |
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