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參數(shù)資料
| 型號： | LM4880 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Dual 250 mW Audio Power Amplifier with Shutdown Mode |
| 中文描述： | 雙250毫瓦音頻功率放大器關斷模式 |
| 文件頁數(shù)： | 10/12頁 |
| 文件大?。?/td> | 375K |
| 代理商： | LM4880 |
Application Information
(Continued)
(4)
(5)
A
V
= R
F
/R
i
From Equation (4) the minimum gain is::
Since the desired input impedance was 20 k
, and with a
gain of 1.26, a value of 27 k
is designated for R
, assum-
ing 5% tolerance resistors. This combination results in a
nominal gain of 1.35. 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 assuming a single
pole roll-off. As stated in the
External Components
section,
both R
in conjunction with C
, and C
with R
, create first or-
der high pass filters. Thus to obtain the desired frequency
low response of 100 Hz within
±
0.5 dB, both poles must be
A
V
= 1.26
taken into consideration. The combination of two single order
filters at the same frequency forms a second order response.
This results in a signal which is down 0.34 dB at five times
away from the single order filter 3 dB point. Thus, a fre-
quency of 20 Hz is used in the following equations to ensure
that the response if better than 0.5 dB down at 100 Hz.
C
i
≥
1/(2
π
*
20k
*
20Hz) = 0.397 μF; use 0.39 μF
C
o
≥
1/(2
π
*
8
*
20Hz) = 995 μF; use 1000 μF
The high frequency pole is determined by the product of the
desired high frequency pole, f
, and the closed-loop gain,
A
. With a closed-loop gain magnitude of 1.35 and f
= 100
kHz, the resulting GBWP = 135 kHz which is much smaller
than the LM4880 GBWP of 12.5 MHz. This figure displays
that if a designer has a need top design an amplifier with a
higher gain, the LM4880 can still be used without running
into bandwidth limitations.
www.national.com
10
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PDF描述 |
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| LM4880N | Dual 250 mW Audio Power Amplifier with Shutdown Mode |
| LM4880M | Dual 250 mW Audio Power Amplifier with Shutdown Mode |
| LM4883 | Dual 2.1W Audio Amplifier Plus Stereo Headphone |
| LM4883SQ | Dual 2.1W Audio Amplifier Plus Stereo Headphone |
| LM4889 | 1 Watt Audio Power Amplifier |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM4880_07 | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:DUAL 250mW AUDIO POWER AMPLIFIER WITH SHUTDOWN MODE |
| LM4880_12 | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:DUAL 250mW AUDIO POWER AMPLIFIER WITH SHUTDOWN MODE |
| LM4880-D08-T | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:DUAL 250mW AUDIO POWER AMPLIFIER WITH SHUTDOWN MODE |
| LM4880G-D08-T | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:DUAL 250mW AUDIO POWER AMPLIFIER WITH SHUTDOWN MODE |
| LM4880G-SH2-R | 制造商:UTC-IC 制造商全稱:UTC-IC 功能描述:DUAL 250mW AUDIO POWER AMPLIFIER WITH SHUTDOWN MODE |
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