参数资料
型号: LM4890ITL/NOPB
厂商: NATIONAL SEMICONDUCTOR CORP
元件分类: 音频/视频放大
英文描述: 1 W, 1 CHANNEL, AUDIO AMPLIFIER, PBGA9
封装: MICRO, SMD-9
文件页数: 13/30页
文件大小: 1621K
代理商: LM4890ITL/NOPB
Application Information (Continued)
As stated in the External Components section, R
IN in con-
junction with C
IN create a highpass filter.
C
IN
≥ 1/(2π*20 k*20Hz) = 0.397F; use 0.39F
The high frequency pole is determined by the product of the
desired frequency pole, f
H, and the differential gain, AVD.
With a A
VD = 3 and fH = 100kHz, the resulting GBWP =
300kHz which is much smaller than the LM4890 GBWP of
2.5MHz. This calculation shows that if a designer has a need
to design an amplifier with a higher differential gain, the
LM4890 can still be used without running into bandwidth
limitations.
The LM4890 is unity-gain stable and requires no external
components besides gain-setting resistors, an input coupling
capacitor, and proper supply bypassing in the typical appli-
cation. However, if a closed-loop differential gain of greater
than 10 is required, a feedback capacitor (C4) may be
needed as shown in Figure 2 to bandwidth limit the amplifier.
This feedback capacitor creates a low pass filter that elimi-
nates possible high frequency oscillations. Care should be
taken when calculating the -3dB frequency in that an incor-
rect combination of R
3
and C
4
will cause rolloff before
20kHz. A typical combination of feedback resistor and ca-
pacitor that will not produce audio band high frequency rolloff
is R
3 = 20k
and C
4 = 25pf. These components result in a
-3dB point of approximately 320 kHz.
20019224
FIGURE 2. HIGHER GAIN AUDIO AMPLIFIER
LM4890
www.national.com
20
相关PDF资料
PDF描述
LM4890ITLX/NOPB 1 W, 1 CHANNEL, AUDIO AMPLIFIER, PBGA9
LM4891MM/NOPB 1 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8
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相关代理商/技术参数
参数描述
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LM4890ITP 制造商:Texas Instruments 功能描述:AMP AUDIO CELLULAR 1W SMD 4890
LM4890ITP/NOPB 功能描述:IC AMP AUDIO PWR 1W MONO 8USMD 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)
LM4890ITPX/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