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參數(shù)資料
| 型號： | LM4863MWC |
| 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： | WAFER |
| 文件頁數(shù)： | 2/22頁 |
| 文件大?。?/td> | 757K |
| 代理商： | LM4863MWC |
Application Information (Continued)
pling capacitor in a single-ended configuration forces a
single-supply amplifier’s half-supply bias voltage across the
load. This increases internal IC power dissipation and may
permanently damage loads such as speakers.
POWER DISSIPATION
Power dissipation is a major concern when designing a suc-
cessful single-ended or bridged amplifier. Equation (2) states
the maximum power dissipation point for a single-ended am-
plifier operating at a given supply voltage and driving a
specified output load
P
DMAX =(VDD)
2 /(2
π2 R
L) Single-Ended
(2)
However, a direct consequence of the increased power de-
livered to the load by a bridge amplifier is higher internal
power dissipation for the same conditions.
The LM4863 has two operational amplifiers per channel. The
maximum internal power dissipation per channel operating in
the bridge mode is four times that of a single-ended ampli-
fier. From Equation (3), assuming a 5V power supply and an
4
load, the maximum single channel power dissipation is
1.27W or 2.54W for stereo operation.
P
DMAX = 4x(VDD)
2 /(2
π2 R
L) Bridge Mode
(3)
The LM4973’s power dissipation is twice that given by Equa-
tion (2) or Equation (3) when operating in the single-ended
mode or bridge mode, respectively. Twice the maximum
power dissipation point given by Equation (3) must not ex-
ceed the power dissipation given by Equation (4):
P
DMAX’= (TJMAX TA)/ θJA
(4)
The LM4863’s T
JMAX = 150C. In the LQ (LLP) package sol-
dered to a DAP pad that expands to a copper area of 5in
2 on
a PCB, the LM4863’s
θ
JA is 20C/W. In the MTE package
soldered to a DAP pad that expands to a copper area of 2in
2
on a PCB , the LM4863’s
θ
JA is 41C/W. At any given ambi-
ent temperature T
J, use Equation (4) to find the maximum
internal power dissipation supported by the IC packaging.
Rearranging Equation (4) and substituting PDMAX for PD-
MAX’ results in Equation (5). This equation gives the maxi-
mum ambient temperature that still allows maximum stereo
power dissipation without violating the LM4863’s maximum
junction temperature.
T
A =TJMAX 2xPDMAX θJA
(5)
For a typical application with a 5V power supply and an 4
load, the maximum ambient temperature that allows maxi-
mum stereo power dissipation without exceeding the maxi-
mum junction temperature is approximately 99C for the LLP
package and 45C for the MTE package.
T
JMAX =PDMAX θJA +TA
(6)
Equation (6) gives the maximum junction temperature T
J-
MAX
. If the result violates the LM4863’s 150C, reduce the
maximum junction temperature by reducing the power sup-
ply voltage or increasing the load resistance. Further allow-
ance should be made for increased ambient temperatures.
The above examples assume that a device is a surface
mount part operating around the maximum power dissipation
point. Since internal power dissipation is a function of output
power, higher ambient temperatures are allowed as output
power or duty cycle decreases.
If the result of Equation (2) is greater than that of Equation
(3), then decrease the supply voltage, increase the load im-
pedance, or reduce the ambient temperature. If these mea-
sures are insufficient, a heat sink can be added to reduce
θ
JA. The heat sink can be created using additional copper
area around the package, with connections to the ground
pin(s), supply pin and amplifier output pins. External, solder
attached SMT heatsinks such as the Thermalloy 7106D can
also improve power dissipation. When adding a heat sink,
the
θ
JA
is the sum of
θ
JC,
θ
CS,
and
θ
SA.(θJC
is the
junctiontocase thermal impedance,
CS is the casetosink
thermal impedance, and
θ
SAis the sinktoambient thermal
impedance.) Refer to the Typical Performance Characteris-
tics curves for power dissipation information at lower output
power levels.
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is criti-
cal for low noise performance and high power supply rejec-
tion. Applications that employ a 5V regulator typically use a
10F in parallel with a 0.1F filter capacitors to stabilize the
regulator’s output, reduce noise on the supply line, and im-
prove the supply’s transient response. However, their pres-
ence does not eliminate the need for a local 1.0F tantalum
bypass capacitance connected between the LM4863’s sup-
ply pins and ground. Do not substitute a ceramic capacitor
for the tantalum. Doing so may cause oscillation in the output
signal. Keep the length of leads and traces that connect ca-
pacitors between the LM4863’s power supply pin and ground
as short as possible. Connecting a 1F capacitor, C
B, 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 amplifier’s click and pop
performance. The selection of bypass capacitor values, es-
pecially C
B, 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 voltage applied to the SHUTDOWN pin controls the
LM4863’s shutdown function. Activate micro-power shut-
down by applying V
DD to the SHUTDOWN pin. When active,
the LM4863’s micro-power shutdown feature turns off the
amplifier’s bias circuitry, reducing the supply current. The
logic threshold is typically V
DD/2. The low 0.7A typical shut-
down current is achieved by applying a voltage that is as
near as V
DD as possible to the SHUTDOWN pin. A voltage
thrat is less than V
DD may increase the shutdown current.
There are a few ways to control the micro-power shutdown.
These include using a single-pole, single-throw switch, a mi-
croprocessor, or a microcontroller. When using a switch,
connect an external 10k
pull-up resistor between the
SHUTDOWN pin and V
DD. Connect the switch between the
SHUTDOWN pin and ground. Select normal amplifier opera-
LM4863
www.national.com
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PDF描述 |
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| 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 |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM4863MX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Engineering Project Manager |
| LM4863MX/NOPB | 功能描述:IC AMP AUDIO PWR 3.2W AB 16SOIC 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: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) |
| LM4863N | 功能描述:IC AMP AUDIO PWR 3.2W STER 16DIP RoHS:否 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: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) |
| LM4864 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:300 mW Audio Power Amplifier with Shutdown Mode |
| LM4864LD/NOPB | 功能描述:IC AMP AUDIO PWR .725W AB 10LLP 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: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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