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参数资料
| 型号： | LM4918LQ/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频控制 |
| 英文描述： | 2 CHANNEL(S), VOLUME CONTROL CIRCUIT, QCC32 |
| 封装： | LLP-32 |
| 文件页数： | 3/17页 |
| 文件大小： | 646K |
| 代理商： | LM4918LQ/NOPB |
Application Information (Continued)
mize thermal design may compromise the LM4918’s perfor-
mance and activate unwanted, though necessary, thermal
shutdown protection.
The LM4918LD must have its DAP soldered to a copper pad
on the PCB. The DAP’s PCB copper pad is then, ideally,
connected to a large plane of continuous unbroken copper.
This plane forms a thermal mass, heat sink, and radiation
area. Place the heat sink area on either outside plane in the
case of a two-sided or multi-layer PCB. (The heat sink area
can also be placed on an inner layer of a multi-layer board.
The thermal resistance, however, will be higher.) Connect
the DAP copper pad to the inner layer or backside copper
heat sink area with 2 vias. The via diameter should be
0.012in - 0.013in with a 1.27mm pitch. Ensure efficient ther-
mal conductivity by plugging and tenting the vias with plating
and solder mask, respectively. Further detailed and specific
information concerning PCB layout, fabrication, and mount-
ing an LQ (LLP) package is available in National Semicon-
ductor’s AN1187.
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is
critical for low noise performance and high power supply
rejection. Applications that employ a 5V regulator typically
use a 10F in parallel with a 0.1F filter capacitors to stabi-
lize the regulator’s output, reduce noise on the supply line,
and improve the supply’s transient response. However, their
presence does not eliminate the need for a local 1.0F
tantalum bypass capacitance connected between the
LM4918’s supply pins and ground. Keep the length of leads
and traces that connect capacitors between the LM4918’s
power supply pin and ground as short as possible. Connect-
ing a 2.2F capacitor, C
B, between the BYPASS pin and
ground improves the internal bias voltage’s stability and
improves the amplifier’s PSRR. The PSRR improvements
increase as the bypass pin capacitor value increases. Too
large, however, increases turn-on time and can compromise
the amplifier’s click and pop performance. The selection of
bypass capacitor values, especially C
B, depends on desired
PSRR requirements, click and pop performance system
cost, and size constraints.
200913I8
FIGURE 2. REFERENCE DESIGN BOARD SCHEMATIC
LM4918
www.national.com
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| LM4919MM/NOPB | 功能描述:IC AMP AUDIO MONO/STER AB 10MSOP 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) |
| LM4919MMBD | 功能描述:BOARDS EVALUATION LM4919MM RoHS:否 类别:编程器，开发系统 >> 评估板 - 音频放大器 系列:Boomer® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- |
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