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參數資料
| 型號： | LM4870M |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 1.1W Audio Power Amplifier with Shutdown Mode |
| 中文描述： | 1.1 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO16 |
| 封裝： | SOIC-16 |
| 文件頁數： | 6/8頁 |
| 文件大?。?/td> | 259K |
| 代理商： | LM4870M |
Application Information
(Continued)
ceeded momentarily, due to the discharging time constant of
the bias-pin voltage. This time constant is established by the
two 50k resistors (in parallel) with the series bypass capaci-
tor value.
When a set of headphones are plugged into the system, the
contact pin of the headphone jack is disconnected from the
signal pin, interrupting the voltage divider set up by resistors
R1 and R2. Resistor R1 then pulls up the HP-IN1 pin, en-
abling the headphone function and disabling the LM4870
amplifier. The headphone amplifier then drives the head-
phones, whose impedance is in parallel with resistor R2.
Since the typical impedance of headphones are 32
, resis-
tor R2 has negligible effect on the output drive capability.
Also shown in Figure 3 are the electrical connections for the
headphone jack and plug. A 3-wire plug consists of a Tip,
Ring, and Sleave, where the Tip and Ring are signal carrying
conductors and the Sleave is the common ground return.
One control pin contact for each headphone jack is sufficient
to indicate to control inputs that the user has inserted a plug
into a jack and that another mode of operation is desired.
For a system implementation where the headphone amplifier
is designed using a split supply, the output coupling cap, C
C
and resistor R2 of Figure 3 can be eliminated. The function-
ality described earlier remains the same, however.
In addition, the HP-SENSE pin, although it may be con-
nected to the SHUTDOWN pin as shown in Figure 2 may
still be used as a control flag. It is capable of driving the input
to another logic gate or approximately 2 mA without serious
loading.
AUDIO POWER AMPLIFIER DESIGN
Design a 500 mW/8
Audio Amplifier
Given:
Power Output:
1.0Wrms
Load Impedance:
8
Input Level:
1 Vrms(max)
Input Impedance:
Bandwidth:
A designer must first determine the needed supply rail to ob-
tain the specified output power. The Output Power vs Supply
Voltage graphs in the
Typical Performance Characteris-
tics
section show how much power the LM4870 will output
given different supply voltage. According to the graph, 4.6V
20 k
100 Hz-20 kHz
±
0.25 dB
DS100094-7
FIGURE 2. HP-SENSE Pin to
SHUTDOWN Pin Connection
DS100094-8
FIGURE 3. Typical Headphone Control Input Circuitry
www.national.com
6
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| LM4871 | 1.1W Audio Power Amplifier with Shutdown Mode |
| LM4871N | 1.1W Audio Power Amplifier with Shutdown Mode |
| LM4871MX | 1.1W Audio Power Amplifier with Shutdown Mode |
| LM4871M | 1.1W Audio Power Amplifier with Shutdown Mode |
| LM4873MTE-1 | Dual 2.1W Audio Amplifier Plus Stereo Headphone Function |
相關代理商/技術參數 |
參數描述 |
|---|---|
| LM4870MX | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| LM4871 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:3W Audio Power Amplifier with Shutdown Mode |
| LM4871_03 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:3W Audio Power Amplifier with Shutdown Mode |
| LM4871LD | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM4871LD/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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