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參數(shù)資料
| 型號： | LM4883SQ/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 0.4 W, 2 CHANNEL, AUDIO AMPLIFIER, QCC24 |
| 封裝： | LLP-24 |
| 文件頁數(shù)： | 7/23頁 |
| 文件大?。?/td> | 1244K |
| 代理商： | LM4883SQ/NOPB |
Application Information (Continued)
BRIDGE CONFIGURATION EXPLANATION
As shown in Figure 3, the LM4883 consists of two pairs of
operational amplifiers, forming a two-channel (channel A and
channel B) stereo amplifier. External feedback resistors
R
3,2,7,8 and input resistors R1,4,5,6 set the closed-loop gain
of Amp A (-out) and Amp B (-out) whereas two internal 20k
resistors set Amp A’s (+out) and Amp B’s (+out) gain at 1.
The LM4883 drives a load, such as a speaker, connected
between the two amplifier outputs, OUTA and +OUTA.
Figure 3 shows that Amp A’s (-out) output serves as Amp A’s
(+out) input. This results in both amplifiers producing signals
identical in magnitude, but 180 out of phase. Taking advan-
tage of this phase difference, a load is placed between
OUTA and +OUTA and driven differentially (commonly re-
ferred to as “bridge mode”). This results in a differential gain
of
A
VD =2*(Rf/R i)
(1)
or
A
VD =2*(R3/R1)
Bridge mode amplifiers are different from single-ended am-
plifiers that drive loads connected between a single amplifi-
er’s output and ground. For a given supply voltage, bridge
mode has a distinct advantage over the single-ended con-
figuration: its differential output doubles the voltage swing
across the load. This produces four times the output power
when compared to a single-ended amplifier under the same
conditions. This increase in attainable output power as-
sumes that the amplifier is not current limited or that the
output signal is not clipped. To ensure minimum output sig-
nal clipping when choosing an amplifier’s closed-loop gain,
refer to the Audio Power Amplifier Design section.
Another advantage of the differential bridge output is no net
DC voltage across the load. This is accomplished by biasing
channel A’s and channel B’s outputs at half-supply. This
eliminates the coupling capacitor that single supply, single-
ended amplifiers require. Eliminating an output coupling ca-
pacitor in a single-ended configuration forces a single-supply
amplifier’s half-supply bias voltage across the load. This
increases internal IC power dissipation and may perma-
nently damage loads such as speakers.
POWER DISSIPATION
Power dissipation is a major concern when designing a
successful single-ended or bridged amplifier. Equation (2)
states the maximum power dissipation point for a single-
ended amplifier operating at a given supply voltage and
driving a specified output load.
P
DMAX =(VDD)
2/(2
π2R
L)
Single-Ended
(2)
However, a direct consequence of the increased power de-
livered to the load by a bridge amplifier is higher internal
power dissipation for the same conditions.
The LM4883 has two operational amplifiers per channel. The
maximum internal power dissipation per channel operating in
the bridge mode is four times that of a single-ended ampli-
fier. From Equation (3), assuming a 5V power supply and a
4
load, the maximum single channel power dissipation is
1.27W or 2.54W for stereo operation.
P
DMAX =4*(VDD)
2/(2
π2R
L)
Bridge Mode
(3)
The LM4883SQ’s power dissipation is twice that given by
Equation (2) or Equation (3) when operating in the single-
ended mode or bridge mode, respectively. Twice the maxi-
mum power dissipation point given by Equation (3) must not
exceed the power dissipation given by Equation (4):
P
DMAX'=(TJMAX TA)/
θ
JA
(4)
The LM4883’s T
JMAX = 150C. In the SQ package soldered
to a DAP pad that expands to a copper area of 5in
2 on a
200887A4
* Refer to the section Selecting Proper External Components, for a detailed discussion of C5 size.
FIGURE 3. Typical Audio Amplifier Application Circuit
LM4883
www.national.com
15
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| LM4883SQX/NOPB | 功能描述:IC AMP AUDIO PWR 3W STER 24LLP 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(jī)，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) |
| LM4884 | 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 RF Suppression and Shutdown |
| LM4884A E WAF | 制造商:Texas Instruments 功能描述: |
| LM4884MH | 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 RF Suppression and Shutdown |
| LM4884MH/NOPB | 功能描述:IC AMP AUDIO 2.6W STER 20TSSOP 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(jī)，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) |
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