参数资料
| 型号： | LM4819M |
| 厂商： | National Semiconductor |
| 文件页数： | 3/27页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR .35W MONO 8SOIC |
| 标准包装： | 95 |
| 系列： | Boomer® |
| 类型： | AB 类 |
| 输出类型： | 1-通道（单声道） |
| 在某负载时最大输出功率 x 通道数量： | 350mW x 1 @ 16 欧姆 |
| 电源电压： | 2 V ~ 5.5 V |
| 特点： | 消除爆音，差分输入，关闭 |
| 安装类型： | 表面贴装 |
| 供应商设备封装： | 8-SOIC |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 其它名称： | *LM4819M |
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SNAS133D – FEBRUARY 2001 – REVISED MARCH 2013
load and a 5V supply is approximately 575mW. Substituting this value back into Equation 4 for PDMAX and using
θJA = 210°C/W for the DGK0008A package, the maximum ambient temperature is calculated to be 29°C. Using
Performance Characteristics curves for power dissipation information for lower output powers and maximum
power dissipation for each package at a given ambient temperature.
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply
rejection. The capacitors connected to the bypass and power supply pins should be placed as close to the
LM4819 as possible. The capacitor connected between the bypass pin and ground improves the internal bias
voltage's stability, producing improved PSRR. The improvements to PSRR increase as the bypass pin capacitor
value increases. Typical applications employ a 5V regulator with 10F and 0.1F filter capacitors that aid in
supply stability. Their presence, however, does not eliminate the need for bypassing the supply nodes of the
LM4819. The selection of bypass capacitor values, especially CB , depends on desired PSRR requirements, click
and pop performance as explained in the section, Proper Selection of External Components, as well as system
cost and size constraints.
SHUTDOWN FUNCTION
The voltage applied to the LM4819's SHUTDOWN pin controls the shutdown function. Activate micro-power
shutdown by applying VDD to the SHUTDOWN pin. When active, the LM4819's micro-power shutdown feature
turns off the amplifier's bias circuitry, reducing the supply current. The logic threshold is typically 1/2VDD. The low
0.7A typical shutdown current is achieved by applying a voltage that is as near as VDD as possible to the
SHUTDOWN pin. A voltage that is less than VDD may increase the shutdown current. Avoid intermittent or
unexpected micro-power shutdown by ensuring that the SHUTDOWN pin is not left floating but connected to
either VDD or GND.
There are a few ways to activate micro-power shutdown. These included using a single-pole, single-throw switch,
a microcontroller, or a microprocessor. When using a switch, connect an external 10k
to 100k pull-up resistor
between the SHUTDOWN pin and VDD. Connect the switch between the SHUTDOWN pin and ground. Select
normal amplifier operation by closing the switch. Opening the switch connects the shutdown pin to VDD through
the pull-up resistor, activating micro-power shutdown. The switch and resistor ensure that the SHUTDOWN pin
will not float. This prevents unwanted state changes. In a system with a microprocessor or a microcontroller, use
a digital output to apply the control voltage to the SHUTDOWN pin. Driving the SHUTDOWN pin with active
circuitry eliminates the pull-up resistor
PROPER SELECTION OF EXTERNAL COMPONENTS
Optimizing the LM4819's performance requires properly selecting external components. Though the LM4819
operates well when using external components with wide tolerances, best performance is achieved by optimizing
component values.
The LM4819 is unity gain stable, giving the designer maximum design flexibility. The gain should be set to no
more than a given application requires. This allows the amplifier to achieve minimum THD+N and maximum
signal-to-noise ratio. These parameters are compromised as the closed-loop gain increases. However, low gain
demands input signals with greater voltage swings to achieve maximum output power. Fortunately, many signal
sources such as audio CODECs have outputs of 1VRMS (2.83VP-P). Please refer to the Audio Power Amplifier
Design section for more information on selecting the proper gain.
Another important consideration is the amplifier's close-loop bandwidth. To a large extent, the bandwidth is
dictated by the choice of external components shown in Figure 1. The input coupling capacitor, Ci, forms a first
order high pass filter that limits low frequency response. This value should be chosen based on needed
frequency response for a few distinct reasons discussed below
Input Capacitor Value Selection
Amplifying the lowest audio frequencies requires a high value input coupling capacitor (Ci in Figure 1). A high
value capacitor can be expensive and may compromise space efficiency in portable designs. In many cases the
speakers used in portable systems, whether internal or external, have little ability to reproduce signals below
150Hz. Applications using speakers with limited frequency response reap little improvement by using a large
input capacitor.
Copyright 2001–2013, Texas Instruments Incorporated
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM4819M/NOPB | 功能描述:IC AMP AUDIO PWR .35W MONO 8SOIC 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) |
| LM4819MBD | 功能描述:音频 IC 开发工具 LM4819M 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 |
| LM4819MBD/NOPB | 功能描述:音频 IC 开发工具 LM4819MBD EVAL MOD 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 |
| LM4819MM | 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 |
| LM4819MM/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 |
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