參數(shù)資料
型號: LM4863MWC
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類: 音頻/視頻放大
英文描述: 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, UUC
封裝: WAFER
文件頁數(shù): 5/22頁
文件大小: 757K
代理商: LM4863MWC
Application Information (Continued)
voltage must also not create a situation that violates maxi-
mum power dissipation as explained above in the Power
Dissipation section.
After satisfying the LM4863’s power dissipation require-
ments, the minimum differential gain is found using Equation
(10).
(10)
Thus, a minimum gain of 2.83 allows the LM4863’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 onefifth 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 de-
sired limit. The results are an
f
L = 100Hz/5 = 20Hz
(12)
and an
F
H = 20kHzx5 = 100kHz
(13)
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 (14).
(14)
the result is
1/(2
π*20k*20Hz) = 0.398F
(15)
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 LM4863’s 3.5MHz GBWP. With
this margin, the amplifier can be used in designs that require
more differential gain while avoiding performance-lrestricting
bandwidth limitations.
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figures 3 through 6 show the recommended two-layer PC
board layout that is optimized for the 20-pin MTE-packaged
LM4863 and associated external components. Figures 7
through 11 show the recommended four-layer PC board lay-
out that is optimized for the 24-pin LQ-packaged LM4863
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.
DS012881-94
Figure 3. MTE PC board layout:
all layers superimposed
DS012881-93
Figure 4. MTE PC board layout:
Component-side Silkscreen
LM4863
www.national.com
13
相關PDF資料
PDF描述
LM4863MX/NOPB 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO16
LM4863MTEX/NOPB 3.2 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20
LM4863MTX/NOPB 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20
LM4863N/NOPB 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDIP16
LM4863LQX/NOPB 3.2 W, 2 CHANNEL, AUDIO AMPLIFIER, QCC24
相關代理商/技術參數(shù)
參數(shù)描述
LM4863MX 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Engineering Project Manager
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LM4864LD/NOPB 功能描述:IC AMP AUDIO PWR .725W 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 供應商設備封裝:25-WLP(2.09x2.09) 封裝/外殼:25-WFBGA,WLCSP 包裝:帶卷 (TR)