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參數(shù)資料
| 型號： | LM4870M |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 1.1W Audio Power Amplifier with Shutdown Mode |
| 中文描述： | 1.1 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO16 |
| 封裝： | SOIC-16 |
| 文件頁數(shù)： | 7/8頁 |
| 文件大?。?/td> | 259K |
| 代理商： | LM4870M |
Application Information
(Continued)
are required for 1.0W of output power. Since 5V rails are
common, it is chosen to be the supply voltage. Supply volt-
age (up to a maximum of 5.5V) above the required 4.6V will
allow the LM4870 to reproduce transient signals at greater
than 1.0W of output power. The extra voltage will also in-
crease the device power dissipation, so the designer must
make sure that the conditions explained in the
Power Dissi-
pation
section are not violated.
Once the power dissipation issues have been addressed,
the required differential gain can be determined from Equa-
tion 4:
From equation 4, the minimum A
vd
is A
vd
= 2.83; use A
vd
=
3.
Since the amplifier output is bridged, giving a gain of 2, and
the desired system gain is 3, the ratio of feedback (R
f
) to in-
put (R
) resistor is 1.5:1. If R
is set to the required input im-
pedance of 20 k
, then R
= 30 k
. The final design step is
to address the bandwidth requirements which must be
stated as a pair of 3 dB frequency points. Five times away
from a 3 dB point is 0.17 dB down from passband response
which is better than the required
±
0.25 dB specified.
f
L
= 100 Hz/5 = 20 Hz
f
= 20 kHz5 = 100 HzAs stated in the
External Compo-
nents
section, R
i
in conjunction with C
i
create a highpass
filter.
C
i
≥
1/(2
π
*
20 k
*
20 Hz) = 0.397 μF;
The high frequency pole is determined by the product of the
desired high frequency pole, f
, and the differential gain, A
vd
. With a A
= 3 and f
= 100 kHz, the resulting GBWP =
150 kHz which is much smaller than the LM4870 GBWP of
4 MHz. This figure displays that if a designer has a need to
design an amplifier with a higher differential gain, the
LM4870 can still be used without running into bandwidth
problems.
use 0.39 μF.
www.national.com
7
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4870MX | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| LM4871 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:3W Audio Power Amplifier with Shutdown Mode |
| LM4871_03 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:3W Audio Power Amplifier with Shutdown Mode |
| LM4871LD | 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 |
| LM4871LD/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 |
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