- 您現(xiàn)在的位置：買賣IC網 > PDF目錄16817 > LM4819MBD (National Semiconductor)BOARD EVALUATION LM4819M PDF資料下載
參數(shù)資料
| 型號： | LM4819MBD |
| 廠商： | National Semiconductor |
| 文件頁數(shù)： | 3/27頁 |
| 文件大?。?/td> | 0K |
| 描述： | BOARD EVALUATION LM4819M |
| 標準包裝： | 1 |
| 系列： | Boomer® |
| 放大器類型： | AB 類 |
| 輸出類型： | 1-通道（單聲道） |
| 在某負載時最大輸出功率 x 通道數(shù)量： | 350mW x 1 @ 16 歐姆 |
| 電源電壓： | 2 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 85°C |
| 板類型： | 完全填充 |
| 已用 IC / 零件： | LM4819 |
| 已供物品： | 板 |
| 相關產品： | LM4819M/NOPB-ND - IC AMP AUDIO PWR .35W MONO 8SOIC LM4819MX/NOPBTR-ND - IC AMP AUDIO PWR .35W MONO 8SOIC LM4819MM-ND - IC AMP AUDIO PWR .35W MONO 8MSOP LM4819MMX-ND - IC AMP AUDIO PWR .35W MONO 8MSOP |
第1頁第2頁當前第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁
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
相關PDF資料 |
PDF描述 |
|---|---|
| 50YXG47MEFC6.3X11 | CAP ALUM 47UF 50V 20% RADIAL |
| NCP2890EVB | EVAL BOARD FOR NCP2890 |
| V150B36E150BF3 | CONVERTER MOD DC/DC 36V 150W |
| 1812R-823J | INDUCTOR UNSHIELDED 82UH SMD |
| RBA10DRMT-S288 | CONN EDGECARD 20POS .125 EXTEND |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM4819MBD/NOPB | 功能描述:音頻 IC 開發(fā)工具 LM4819MBD EVAL MOD RoHS:否 制造商:Texas Instruments 產品:Evaluation Kits 類型:Audio Amplifiers 工具用于評估:TAS5614L 工作電源電壓:12 V to 38 V |
| LM4819MM | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4819MM/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4819MMX | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4819MMX/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復。