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參數資料
| 型號： | LM4873MTEX-1/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 3 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO28 |
| 封裝： | 9.70 X 4.40 MM, 0.90 MM HEIGHT, TSSOP-28 |
| 文件頁數： | 10/25頁 |
| 文件大?。?/td> | 963K |
| 代理商： | LM4873MTEX-1/NOPB |
Application Information (Continued)
without clipping or other audible distortion. The choice of
supply voltage must also not create a situation that violates
maximum power dissipation as explained above in the
Power Dissipation section.
After satisfying the LM4873’s power dissipation require-
ments, the minimum differential gain needed to achieve 1W
dissipation in an 8
load is found using Equation (10).
(10)
Thus, a minimum gain of 2.83 allows the LM4873’s to reach
full output swing and maintain low noise and THD+N perfor-
mance. For this example, let A
VD =3.
The amplifier’s overall gain is set using the input (R
i) and
feedback (R
f) resistors. With the desired input impedance
set at 20k
, the feedback resistor is found using Equation
(11).
R
f/Ri =AVD/2
(11)
The value of R
f is 30k
.
The last step in this design example is setting the amplifier’s
3dB 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
and an
f
H = 20kHz*5 = 100kHz.
As mentioned in the External Components section, R
i and
C
i create a highpass filter that sets the amplifier’s lower
bandpass frequency limit. Find the coupling capacitor’s
value using Equation (12).
C
i
≥ 1/(2πR
ifL)
(12)
The result is
1/(2
π*20k*20Hz) = 0.398F.
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, AVD, 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 LM4873’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 4 through 6 show the recommended two-layer PC
board layout that is optimized for the 20-pin MTE-packaged
LM4873 and associated external components. Figures 7
through 11 show the recommended four-layer PC board
layout that is optimized for the 24-pin LQ-packaged LM4873
and associated external components. Figures 12 through 16
show the recommended four-layer PC board layout that is
optimized for the 20-pin micro SMD-packaged LM4873 and
associated external components. These circuits are de-
signed for use with an external 5V supply and 4
speakers.
These circuit boards are easy to use. Apply 5V and ground to
the board’s V
DD and GND pads, respectively. Connect 4
speakers between the board’s OUTA and +OUTA and
OUTB and +OUTB pads.
10099393
FIGURE 4. Recommended MTE PC Board Layout:
Component-Side Silkscreen
10099391
FIGURE 5. Recommended MTE PC Board Layout:
Component-Side Layout
10099392
FIGURE 6. Recommended MTE PC Board Layout:
Bottom-Side Layout
LM4873
www.national.com
18
相關PDF資料 |
PDF描述 |
|---|---|
| LM4873MT/NOPB | 1.9 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
| LM4873MTX/NOPB | 1.9 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
| LM4873ITL/NOPB | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PBGA20 |
| LM4873ITLX/NOPB | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PBGA20 |
| LM4873LQ/NOPB | 3 W, 2 CHANNEL, AUDIO AMPLIFIER, QCC24 |
相關代理商/技術參數 |
參數描述 |
|---|---|
| LM4873MTX | 功能描述:IC AMP AUDIO PWR 3W STER 20TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 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: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 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4874 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:2.1W Differential Input, BTL Output Stereo Audio Amplifier with Selectable Gain and Shutdown |
| LM4874MH | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:2.1W Differential Input, BTL Output Stereo Audio Amplifier with Selectable Gain and Shutdown |
| LM4874MH/NOPB | 功能描述:IC AMP AUDIO PWR 2.6W AB 20TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 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: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 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4875 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:750 mW Audio Power Amplifier with DC Volume Control and Headphone Switch |
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