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參數(shù)資料
| 型號(hào)： | LM4863MDC |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, UUC |
| 封裝： | DIE |
| 文件頁數(shù)： | 3/22頁 |
| 文件大小： | 757K |
| 代理商： | LM4863MDC |
Application Information (Continued)
tion by closing the switch. Opening the switch connects the
SHUTDOWN pin to V
DD through the pull-up resistor, activat-
ing micro-power shutdown. The switch and resistor guaran-
tee that the SHUTDOWN pin will not float. This prevents un-
wanted 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.
Table 1. Logic level truth table for
SHUTDOWN and HP-IN operation
SHUTDOWN
HP-IN PIN
OPERATIONAL
MODE
Low
logic Low
Bridged amplifiers
Low
logic High
Single-Ended
amplifiers
High
logic Low
Micro-power Shutdown
High
logic High
Micro-power Shutdown
HP-IN FUNCTION
Applying a voltage between 4V and V
DD to the LM4863’s
HP-IN headphone control pin turns off Amp2A and Amp2B,
muting a bridged-connected load. Quiescent current con-
sumption is reduced when the IC is in this single-ended
mode.
Figure 2 shows the implementation of the LM4863’s head-
phone control function. With no headphones connected to
the headphone jack, the R1-R2 voltage divider sets the volt-
age applied to the HP-IN pin (pin 16) at approximately 50mV.
This 50mV enables Amp1B and Amp2B, placing the
LM4863’s in bridged mode operation. The output coupling
capacitor blocks the amplifier’s half-supply DC voltage, pro-
tecting the headphones.
The HP-IN threshold is set at 4V. While the LM4863 operates
in bridged mode, the DC potential across the load is essen-
tially 0V. Therefore, even in an ideal situation, the output
swing cannot cause a false single-ended trigger. Connecting
headphones to the headphone jack disconnects the head-
phone jack contact pin from -OUTA and allows R1 to pull the
HP Sense pin up to V
DD. This enables the headphone func-
tion, turns off Amp2A and Amp2B, and mutes the bridged
speaker. The amplifier then drives the headphones, whose
impedance is in parallel with resistor R2 and R3. These re-
sistors have negligible effect on the LM4863’s output drive
capability since the typical impedance of headphones is
32
.
Figure 2 also shows the suggested headphone jack electri-
cal connections. The jack is designed to mate with a
three-wire plug. The plug’s tip and ring should each carry
one of the two stereo output signals, whereas the sleeve
should carry the ground return. A headphone jack with one
control pin contact is sufficient to drive the HP-IN pin when
connecting headphones.
A microprocessor or a switch can replace the headphone
jack contact pin. When a microprocessor or switch applies a
voltage greater than 4V to the HP-IN pin, a bridge-connected
speaker is muted and Amp1A and Amp2A drive a pair of
headphones.
SELECTING PROPER EXTERNAL COMPONENTS
Optimizing the LM4863’s performance requires properly se-
lecting external components. Though the LM4863 operates
well when using external components with wide tolerances,
best performance is achieved by optimizing component val-
ues.
The LM4863 is unity-gain stable, giving a 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 ra-
tio. 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 CO-
DECs have outputs of 1V
RMS (2.83VP-P). Please refer to the
Audio Power Amplifier Design section for more informa-
tion on selecting the proper gain.
Input Capacitor Value Selection
Amplifying the lowest audio frequencies requires high value
input coupling capacitor (C
i in Figure 1). A high value capaci-
tor can be expensive and may compromise space efficiency
in portable designs. In many cases, however, the speakers
used in portable systems, whether internal or external, have
little ability to reproduce signals below 150Hz. Applications
using speakers with this limited frequency response reap
little improvement by using large input capacitor.
Besides effecting system cost and size, C
i has an affect on
the LM4863’s click and pop performance. When the supply
voltage is first applied, a transient (pop) is created as the
DS012881-24
FIGURE 2. Headphone Circuit
LM4863
www.national.com
11
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM4863MWC | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, UUC |
| LM4863MX/NOPB | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO16 |
| LM4863MTEX/NOPB | 3.2 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
| LM4863MTX/NOPB | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO20 |
| LM4863N/NOPB | 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, PDIP16 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4863MT | 制造商:Panasonic Industrial Company 功能描述:IC |
| LM4863MT | 制造商:Texas Instruments 功能描述:AMP AUDIO DUAL 2.2W 4863 TSSOP20 |
| LM4863MT/NOPB | 功能描述:IC AMP AUDIO PWR 3.2W AB 20TSSOP 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) |
| LM4863MTE | 制造商:Texas Instruments 功能描述:Audio Amp Headphone/Speaker 2-CH Stereo 3.2W Class-AB 20-Pin TSSOP EP Rail 制造商:Texas Instruments 功能描述:IC, AUDIO PWR AMP CLASS AB 2.5W TSSOP-16, Amplifier Class:AB, No. of Channels:2, 制造商:Texas Instruments 功能描述:Audio Amplifier Circuit, Dual, 20 Pin, Plastic, TSSOP |
| LM4863MTE/NOPB | 功能描述:IC AMP AUDIO PWR 3.2W AB 20TSSOP 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) |
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