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參數(shù)資料
| 型號(hào)： | LM4913 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 2W Monaural, 90mW Stereo Headphone Audio Amplifier |
| 中文描述： | 2W的單聲道，立體聲耳機(jī)90兆瓦音頻放大器 |
| 文件頁(yè)數(shù)： | 11/15頁(yè) |
| 文件大小： | 767K |
| 代理商： | LM4913 |
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Application Information
(Continued)
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 10μF in parallel with a 0.1μF 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 0.47μF
tantalum bypass capacitance connected between the
LM4913’s supply pins and ground. Do not substitute a ce-
ramic capacitor for the tantalum. Doing so may cause oscil-
lation.
Keep the length of leads and traces that connect capacitors
between the LM4913’s power supply pin and ground as
short as possible. Connecting a 0.47μF capacitor, CB, be-
tween 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 ca-
pacitor 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 CB, depends on desired PSRR requirements,
click and pop performance (as explained in the section,
Proper Selection of External Components), system cost, and
size constraints.
MICRO-POWER SHUTDOWN
The LM4913 features an active-low micro-power shutdown
mode. When active, the LM4913’s micro-power shutdown
feature turns off the amplifier’s bias circuitry, reducing the
supply current. The logic threshold is typically VDD/2. The
low 0.1μAtypical shutdown current is achieved by applying a
voltage to the SHUTDOWN pin that is as near to GND as
possible. A voltage that is greater than GND may increase
the shutdown current.
There are a few methods to control the micro-power shut-
down. These include using a single-pole, single-throw switch
(SPST), a microprocessor, or a microcontroller. When using
a switch, connect a 100kW pull-up resistor between the
SHUTDOWN pin and VDD and the SPST switch between
the SHUTDOWN pin and GND. Select normal amplifier op-
eration by opening the switch. Closing the switch applies
GND to the SHUTDOWN pin, activating micro-power shut-
down. The switch and resistor guarantee that the SHUT-
DOWN pin will not float. This prevents unwanted state
changes. In a system with a microprocessor or a microcon-
troller, use a digital output to apply the active-state voltage to
the SHUTDOWN pin.
HEADPHONE (SINGLE-ENDED) AMPLIFIER
OPERATION
BTL/SE [Mono (BTL)/Stereo (SE)] Function
Applying a voltage greater than 0.9VDD to the LM4913’s
BTL/SE headphone control pin switches the amplifier’s op-
eration from mono BTL to stereo SE. Applying a voltage less
than 0.55VDD to the LM4913’s BTL/SE headphone control
pin switches the amplifier’s operation from stereo SE to
mono BTL.
Figure 3 shows how to control the LM4913’s headphone
function using four external resistors and a dual-switch ste-
reo headphone jack. External resistors R4 - R6 provide the
control voltages that are applied through the upper head-
phone jack switch. R6 and R7 provide a DC return path for
the SE coupling capacitors.
{Resume here and check other Fig. 3 below.} With no head-
phones connected to the headphone jack, the R5-R6 voltage
divider sets the voltage applied to the BTL/SE pin (pin 7) at
approximately 50mV (comfortably below the 0.55VDD logic-
low threshold). This 50mV tells the LM4913 to select the
signal applied to the MONO-IN input and places the LM4913
in mono BTL operation. When stereo SE operation is de-
sired, both headphone jack switches are opened with a
headphone plug. Opening the lower one allows R5 to apply
VDD to the BTL/SE pin. This switches the amplifier’s inputs
to the stereo signal. Opening the lower one breaks the
connection between AMP4’s output and the BTL speaker,
200617A1
FIGURE 3. Headphone Operation and BTL - SE Mode Switching
L
www.national.com
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM4913MH | 2W Monaural, 90mW Stereo Headphone Audio Amplifier |
| LM4913MM | 2W Monaural, 90mW Stereo Headphone Audio Amplifier |
| LM4917 | Ground-Referenced, 95mW Stereo Headphone Amplifier |
| LM4917MT | Ground-Referenced, 95mW Stereo Headphone Amplifier |
| LM4917SD | Ground-Referenced, 95mW Stereo Headphone Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4913A WAF | 制造商:Texas Instruments 功能描述: |
| LM4913MH | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM4913MH/NOPB | 功能描述:IC AMP AUDIO MONO/STER 10TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，2-通道（立體聲） 在某負(fù)載時(shí)最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點(diǎn):I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4913MHX/NOPB | 制造商:Texas Instruments 功能描述:Audio Amp Headphone/Speaker 1-CH Mono/2-CH Stereo 2W Class-AB 10-Pin TSSOP EP T/R |
| LM4913MM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:2W Monaural, 90mW Stereo Headphone Audio Amplifier |
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