- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄30753 > LM4863MDC (NATIONAL SEMICONDUCTOR CORP) 1.5 W, 2 CHANNEL, AUDIO AMPLIFIER, UUC PDF資料下載
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)： | 4/22頁 |
| 文件大?。?/td> | 757K |
| 代理商： | LM4863MDC |
Application Information (Continued)
charge on the input capacitor changes from zero to a quies-
cent state. The magnitude of the pop is directly proportional
to the input capacitor’s size. Higher value capacitors need
more time to reach a quiescent DC voltage (usually V
DD/2)
when charged with a fixed current. The amplifier’s output
charges the input capacitor through the feedback resistor,
R
f. Thus, pops can be minimized by selecting an input ca-
pacitor value that is no higher than necessary to meet the
desired -3dB frequency.
A shown in
Figure 1, the input resistor (R
I) and the input ca-
pacitor, C
I produce a 3dB high pass filter cutoff frequency
that is found using Equation (7).
(7)
As an example when using a speaker with a low frequency
limit of 150Hz, C
I, using Equation (4), is 0.063F. The 1.0F
C
I shown in Figure 1 allows the LM4863 to drive high effi-
ciency, full range speaker whose response extends below
30Hz.
Bypass Capacitor Value Selection
Besides minimizing the input capacitor size, careful consid-
eration should be paid to value of C
B, the capacitor con-
nected to the BYPASS pin. Since C
B determines how fast
the LM4863 settles to quiescent operation, its value is critical
when minimizing turnon pops. The slower the LM4863’s
outputs ramp to their quiescent DC voltage (nominally 1/2
V
DD), the smaller the turnon pop. Choosing CB equal to
1.0F along with a small value of C
i (in the range of 0.1F to
0.39F), produces a click-less and pop-less shutdown func-
tion. As discussed above, choosing C
i no larger than neces-
sary for the desired bandwidth helps minimize clicks and
pops.
OPTIMIZING CLICK AND POP REDUCTION PERFOR-
MANCE
The LM4863 contains circuitry to minimize turn-on and shut-
down transients or ’clicks and pop’. For this discussion,
turn-on refers to either applying the power supply voltage or
when the shutdown mode is deactivated. While the power
supply is ramping to its final value, the LM4863’s internal
amplifiers are configured as unity gain buffers. An internal
current source changes the voltage of the BYPASS pin in a
controlled, linear manner. Ideally, the input and outputs track
the voltage applied to the BYPASS pin. The gain of the inter-
nal amplifiers remains unity until the voltage on the bypass
pin reaches 1/2 V
DD. As soon as the voltage on the BYPASS
pin is stable, the device becomes fully operational. Although
the bypass pin current cannot be modified, changing the size
of C
B alters the device’s turn-on time and the magnitude of
’clicks and pops’. Increasing the value of C
B reduces the
magnitude of turn-on pops. However, this presents a
tradeoff: as the size of C
B increases, the turn-on time in-
creases. There is a linear relationship between the size of C
B
and the turn-on time. Here are some typical turn-on times for
various values of C
B:
C
B
T
ON
0.01F
20 ms
0.1F
200 ms
0.22F
440 ms
0.47F
940 ms
1.0F
2 Sec
In order eliminate ’clicks and pops’, all capacitors must be
discharged before turn-on. Rapidly switching V
DD may not
allow the capacitors to fully discharge, which may cause
’clicks and pops’. In a single-ended configuration, the output
is coupled to the load by C
OUT. This capacitor usually has a
high value. C
OUT discharges through internal 20k resistors.
Depending on the size of C
OUT, the discharge time constant
can be relatively large. To reduce transients in single-ended
mode, an external 1k
-5k resistor can be placed in par-
allel with the internal 20k
resistor. The tradeoff for using
this resistor is increased quiescent current.
NO LOAD STABILITY
The LM4863 may exhibit low level oscillation when the load
resistance is greater than 10k
. This oscillation only occurs
as the output signal swings near the supply voltages. Pre-
vent this oscillation by connecting a 5k
between the output
pins and ground.
AUDIO POWER AMPLIFIER DESIGN
Audio Amplifier Design: Driving 1W into an 8
Load
The following are the desired operational parameters:
Power Output:
1Wrms
Load Impedance:
8
Input Level:
1Vrms
Input Impedance:
20k
Bandwidth:
100Hz20 kHz ± 0.25 dB
The design begins by specifying the minimum supply voltage
necessary to obtain the specified output power. One way to
find the minimum supply voltage is to use the Output Power
vs Supply Voltage curve in the Typical Performance Char-
acteristics section. Another way, using Equation (4), is to
calculate the peak output voltage necessary to achieve the
desired output power for a given load impedance. To ac-
count for the amplifier’s dropout voltage, two additional volt-
ages, based on the Dropout Voltage vs Supply Voltage in the
Typical Performance Characteristics curves, must be
added to the result obtained by Equation (8). The result in
Equation (9).
(8)
V
DD ≥ (VOUTPEAK +(VODTOP +VODBOT))
(9)
The Output Power vs Supply Voltage graph for an 8
load
indicates a minimum supply voltage of 4.6V. This is easily
met by the commonly used 5V supply voltage. The additional
voltage creates the benefit of headroom, allowing the
LM4863 to produce peak output power in excess of 1W with-
out clipping or other audible distortion. The choice of supply
LM4863
www.national.com
12
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) |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。