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参数资料
| 型号： | LM4884MH/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 2.6 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
| 封装： | TSSOP-20 |
| 文件页数： | 7/22页 |
| 文件大小： | 1189K |
| 代理商： | LM4884MH/NOPB |
Typical Performance Characteristics (Continued)
Cross Talk vs Frequency
201163D6
V
DD = 3V, RL =8
,A
V = 21.6dB,
A = Left channel driven, right channel measured;
B = Right channel driven, left channel measured
Application Information
OPTIMIZING RF IMMUNITY
The internal circuitry of the LM4884 suppresses the amount
of RF signal that is coupled into the chip. However, certain
external factors, such as output trace length, output trace
orientation, distance between the chip and the antenna,
antenna strength, speaker type, and type of RF signal, may
affect the RF immunity of the LM4884. In general, the RF
immunity of the LM4884 is application specific. Neverthe-
less, optimal RF immunity can be achieved by using short
output traces and increasing the distance between the
LM4884 and the antenna.
PCB LAYOUT AND SUPPLY REGULATION
CONSIDERATIONS FOR DRIVING 3W AND 4W LOADS
Power dissipated by a load is a function of the voltage swing
across the load and the load’s impedance. As load imped-
ance decreases, load dissipation becomes increasingly de-
pendent on the interconnect (PCB trace and wire) resistance
between the amplifier output pins and the load’s connec-
tions. Residual trace resistance causes a voltage drop,
which results in power dissipated in the trace and not in the
load as desired. For example, 0.1
trace resistance reduces
the output power dissipated by a 4
load from 2.1W to 2.0W.
This problem of decreased load dissipation is exacerbated
as load impedance decreases. Therefore, to maintain the
highest load dissipation and widest output voltage swing,
PCB traces that connect the output pins to a load must be as
wide as possible.
Poor power supply regulation also adversely affects maxi-
mum output power. A poorly regulated supply’s output volt-
age decreases with increasing load current. Reduced supply
voltage causes decreased headroom, output signal clipping,
and reduced output power. Even with tightly regulated sup-
plies, trace resistance creates the same effects as poor
supply regulation. Therefore, making the power supply
traces as wide as possible helps maintain full output voltage
swing.
BRIDGE CONFIGURATION EXPLANATION
As shown in Figure 1, each of the LM4884’s stereo channels
consists of two operational amplifiers. The LM4884 can be
used to drive a speaker connected between the two outputs
of each channel’s amplifiers.
Figure 1 shows that the output of Amp1 serves as the input
to Amp2, which 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
OUT+ and OUT- and driven differentially (commonly referred
to as "bridge mode"). This results in a differential gain of
A
VD = 2(RF/RI)
(1)
Bridge mode is different from single-ended amplifiers that
drive loads connected between a single amplifier’s output
and ground. For a given supply voltage, bridge mode has a
distinct advantage over the single-ended configuration: its
differential output doubles the voltage swing across the load.
This results in four times the output power when compared
to a single-ended amplifier under the same conditions. This
increase in attainable output assumes that the amplifier is
not current limited or the output signal is not clipped. To
ensure minimum output signal clipping when selecting one
of the amplifier’s four closed-loop gains, refer to the Audio
Power Amplifier Design section.
Another advantage of the differential bridge output is no net
DC voltage across the load. This results from biasing OUT+
and OUT- at half-supply. This eliminates the coupling capaci-
tor that single supply, single-ended amplifiers require. Elimi-
nating an output coupling capacitor in a single-ended con-
figuration forces a single supply amplifier’s half-supply bias
voltage across the load. The current flow created by the
half-supply bias voltage increases internal IC power dissipa-
tion and may permanently damage loads such as speakers.
LM4884
www.national.com
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM4884MHX/NOPB | 功能描述:IC AMP AUDIO 2.6W STER 20TSSOP RoHS:是 类别:集成电路 (IC) >> 线性 - 音頻放大器 系列:Boomer® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:DirectDrive® 类型:H 类 输出类型:耳机，2-通道（立体声） 在某负载时最大输出功率 x 通道数量:35mW x 2 @ 16 欧姆 电源电压:1.62 V ~ 1.98 V 特点:I²C，麦克风，静音，短路保护，音量控制 安装类型:表面贴装 供应商设备封装:25-WLP（2.09x2.09） 封装/外壳:25-WFBGA，WLCSP 包装:带卷 (TR) |
| LM48860 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Ground-Referenced, Ultra Low Noise, Fixed Gain Stereo Headphone Amplifier |
| LM48860TL | 制造商:Texas Instruments 功能描述:Audio Amp Headphone 2-CH Stereo 0.05W Class-AB 12-Pin Micro SMD T/R 制造商:Texas Instruments 功能描述:CLASS D AMP, STERO, 0.04W, 12MICRO |
| LM48860TL/NOPB | 功能描述:音频放大器 RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| LM48860TLBD | 功能描述:音频 IC 开发工具 LM48860TL EVAL BOARD RoHS:否 制造商:Texas Instruments 产品:Evaluation Kits 类型:Audio Amplifiers 工具用于评估:TAS5614L 工作电源电压:12 V to 38 V |
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