- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄30753 > LM4841LQ/NOPB (NATIONAL SEMICONDUCTOR CORP) 2 CHANNEL(S), VOLUME CONTROL CIRCUIT, QCC28 PDF資料下載
參數(shù)資料
| 型號： | LM4841LQ/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻控制 |
| 英文描述： | 2 CHANNEL(S), VOLUME CONTROL CIRCUIT, QCC28 |
| 封裝： | LLP-28 |
| 文件頁數(shù)： | 15/31頁 |
| 文件大小： | 1138K |
| 代理商： | LM4841LQ/NOPB |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁當前第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁
Application Information (Continued)
AUDIO POWER AMPLIFIER DESIGN
Audio Amplifier Design: Driving 1W into an 8
Load
The following are the desired operational parameters:
Power Output:
1 W
RMS
Load Impedance:
8
Input Level:
1 V
RMS
Input Impedance:
20 k
Bandwidth:
100 Hz20 kHz ± 0.25 dB
The design begins by specifying the minimum supply voltage
necessary to obtain the specified output power. One way to
find the minimum supply voltage is to use the Output Power
vs Supply Voltage curve in the Typical Performance Char-
acteristics section. Another way, using Equation (10), is to
calculate the peak output voltage necessary to achieve the
desired output power for a given load impedance. To ac-
count for the amplifier’s dropout voltage, two additional volt-
ages, based on the Dropout Voltage vs Supply Voltage in the
Typical Performance Characteristics curves, must be
added to the result obtained by Equation (10). The result is
Equation (11).
(11)
V
DD
≥ (V
OUTPEAK+(VODTOP +VODBOT))
(12)
The Output Power vs Supply Voltage graph for an 8
load
indicates a minimum supply voltage of 4.6V. This is easily
met by the commonly used 5V supply voltage. The additional
voltage creates the benefit of headroom, allowing the
LM4841 to produce peak output power in excess of 1W
without clipping or other audible distortion. The choice of
supply voltage must also not create a situation that violates
of maximum power dissipation as explained above in the
Power Dissipation section.
After satisfying the LM4841’s power dissipation require-
ments, the minimum differential gain needed to achieve 1W
dissipation in an 8
load is found using Equation (12).
(13)
Thus, a minimum overall gain of 2.83 allows the LM4841’s to
reach full output swing and maintain low noise and THD+N
performance.
The last step in this design example is setting the amplifier’s
6dB frequency bandwidth. To achieve the desired ±0.25dB
pass band magnitude variation limit, the low frequency re-
sponse must extend to at least one-fifth the lower bandwidth
limit and the high frequency response must extend to at least
five times the upper bandwidth limit. The gain variation for
both response limits is 0.17dB, well within the ±0.25dB
desired limit. The results are an
f
L = 100Hz/5 = 20Hz
(14)
and an
f
H = 20kHz x 5 = 100kHz
(15)
As mentioned in the Selecting Proper External Compo-
nents section, R
in A and B and Cin A and B create a highpass
filter that sets the amplifier’s lower bandpass frequency limit.
Find the input coupling capacitor’s value using Equation
(14).
C
in A and B
≥ 1/(2πR
in A and BfL)
(16)
The result is
1/(2
π*20k*20Hz) = 0.397F
(17)
Use a 0.39F capacitor, the closest standard value.
The product of the desired high frequency cutoff (100kHz in
this example) and the differential gain A
VD, determines the
upper passband response limit. With A
VD = 3 and fH =
100kHz, the closed-loop gain bandwidth product (GBWP) is
300kHz. This is less than the LM4841’s 3.5MHz GBWP. With
this margin, the amplifier can be used in designs that require
more differential gain while avoiding performance,restricting
bandwidth limitations.
Recommended Printed Circuit
Board Layout
Figures 8 through 14 show the recommended PC board
layout that is optimized for the LM4841 and associated
external components. This circuit is designed for use with an
external 5V supply and 8
speakers.
This circuit board is easy to use. Apply 5V and ground to the
board’s V
DD
and GND pads, respectively. Connect 8
speakers between the board’s OUTA and +OUTA and
-OUTB and +OUTB pads.
LM4841
www.national.com
22
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM4842MHX/NOPB | 2 CHANNEL(S), TONE CONTROL CIRCUIT, PDSO28 |
| LM4842MTX/NOPB | 2 CHANNEL(S), TONE CONTROL CIRCUIT, PDSO28 |
| LM4843MH/NOPB | 2 CHANNEL(S), VOLUME CONTROL CIRCUIT, PDSO20 |
| LM4843MHX/NOPB | 2 CHANNEL(S), VOLUME CONTROL CIRCUIT, PDSO20 |
| LM4850MM/NOPB | 0.3 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO10 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4841MH | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive |
| LM4841MH/NOPB | 功能描述:IC AMP AUDIO PWR 2.2W AB 28TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝: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，靜音，短路保護，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) |
| LM4841MT | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive |
| LM4841MT/NOPB | 功能描述:IC AMP AUDIO PWR 2.2W AB 28TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝: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，靜音，短路保護，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) |
| LM4842 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Stereo 2W Amplifiers with DC Volume Control Transient Free Outputs, and Cap-less Headphone Drive |
發(fā)布緊急采購，3分鐘左右您將得到回復。