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參數(shù)資料
| 型號： | LM4911 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Stereo 40mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output |
| 中文描述： | 40mW的功率立體聲耳機放大器，低噪聲與耦合模式或無需輸出電容可選 |
| 文件頁數(shù)： | 17/18頁 |
| 文件大?。?/td> | 923K |
| 代理商： | LM4911 |
Application Information
(Continued)
allows the LM4911 to reproduce peak in excess of 25mW
without producing audible distortion. At this time, the de-
signer must make sure that the power supply choice along
with the output impedance does not violate the conditions
explained in the
Power Dissipation
section.
Once the power dissipation equations have been addressed,
the required gain can be determined from Equation 2.
(4)
From Equation 4, the minimum A
is 0.89; use A
= 1. Since
the desired input impedance is 20k
, and with a A
gain of
1, a ratio of 1:1 results from Equation 1 for R
f
to R
. The
values are chosen with R
= 20k
and R
= 20k
. The final
design step is to address the bandwidth requirements which
must be stated as a pair of -3dB frequency points. Five times
away from a -3dB point is 0.17dB down from passband
response which is better than the required
±
0.25dB speci-
fied.
f
L
= 100Hz/5 = 20Hz
f
H
= 20kHz * 5 = 100kHz
As stated in the
External Components
section, R
i
in con-
junction with C
i
creates a
C
i
≥
1 / (2
π
* 20k
* 20Hz) = 0.397μF; use 0.39μF.
The high frequency pole is determined by the product of the
desired frequency pole, f
, and the differential gain, A
. With
an A
= 1 and f
= 100kHz, the resulting GBWP = 100kHz
which is much smaller than the LM4911 GBWP of 10MHz.
This figure displays that is a designer has a need to design
an amplifier with higher differential gain, the LM4911 can still
be used without running into bandwidth limitations.
Figure 4 shows an optional resistor connected between the
amplifier output that drives the headphone jack sleeve and
ground. This resistor provides a ground path that supressed
power supply hum. Thishum may occur in applications such
as notebook computers in a shutdown condition and con-
nected to an external powered speaker. The resistor’s 100
value is a suggested starting point. Its final value must be
determined based on the tradeoff between the amount of
noise suppression that may be needed and minimizing the
additional current drawn by the resistor (25mA for a 100
resistor and a 5V supply).
ESD PROTECTION
As stated in theAbsolute Maximum Ratings, the LM4911 has
a maximum ESD susceptibility rating of 2000V. For higher
ESD voltages, the addition of a PCDN042 dual transil (from
California Micro Devices), as shown in Figure 4, will provide
additional protection.
200314B4
Figure 4. The PCDN042 provides additional ESD protection beyond the 2000V shown in the
Absolute Maximum Ratings for the V
O
C output
L
www.national.com
17
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM4911MM | Stereo 40mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output |
| LM4915 | Pseudo-Differential Mono Headphone Amplifier with Fixed 6dB Gain |
| LM4916 | 1.5V, Mono 85mW BTL Output, 14mW Stereo Headphone Audio Amplifier |
| LM4916LD | 1.5V, Mono 85mW BTL Output, 14mW Stereo Headphone Audio Amplifier |
| LM4916MM | 1.5V, Mono 85mW BTL Output, 14mW Stereo Headphone Audio Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4911LD | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Stereo 40mW Low Noise Headphone Amplifier with Selectable Capacitive Coupled or OCL Output |
| LM4911LD/NOPB | 功能描述:IC AMP AUDIO PWR .145W AB 10LLP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負(fù)載時最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4911LDX | 功能描述:IC AMP AUDIO PWR .145W AB 10LLP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負(fù)載時最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4911MM | 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 |
| LM4911MM/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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