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參數資料
| 型號： | LM4868LQ |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function |
| 中文描述： | 3 W, 2 CHANNEL, AUDIO AMPLIFIER, PQCC24 |
| 封裝： | EXPOSED PAD, PLASTIC, LLP-24 |
| 文件頁數： | 13/28頁 |
| 文件大小： | 792K |
| 代理商： | LM4868LQ |
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Application Information
(Continued)
STEREO-INPUT MULTIPLEXER (STEREO MUX)
The LM4868 has two stereo inputs. The MUX CTRL Pin
controls which stereo input is active. As shown in the
Truth
Table for Logic Inputs
, applying 0V to the MUX CTRL input
activates stereo input 1, whereas applying V
to the MUX
CTRL inputs activates stereo input 2. To ensure correct
amplifier operation, unused MUX inputs should be tied to
GND.
Typical LM4868 applications use the MUX to switch between
two stereo input signals. Each stereo channel’s gain can be
tailored to produce the required output signal level by choos-
ing the appropriate input and feedback resistor ratio.
Another configuration uses the MUX to select two different
gains or frequency compensated gains that amplify a single
pair of stereo input signals.
Figure 5
shows two different
feedback networks, Network 1 and Network 2. Network 1
produces increasing gain as the input signal’s frequency
decreases. This can be used to compensate a small,
full-range speaker’s low frequency response roll-off. Network
2 sets the gain for an alternate load such as headphones.
The circuit in
Figure 6
uses Network 1 when driving external
speakers, switching to Network 2 when headphones are
connected. The normally closed control switch in
Figure 6
’s
headphone jack connects to the MUX CTRL pin. When
headphones are connected, the LM4868’s internal pull-up
that applies V
DD
to the HP-IN and the external 100k
resis-
tor applies V
to MUX CTRL pin. Simultaneously applying
these control voltages automatically selects the amplifier
(headphone or bridge) and switches the gain (MUX channel
selection). Alternatively, leaving the MUX CTRL pin indepen-
dently accessible allows a user to select bass boost as
needed. This alternative user-selectable bass-boost scheme
requires connecting equal ratio resistor feedback networks
to each MUX input channel. The value of the resistor in the
RC network is chosen to give a gain that is necessary to
achieve the desired bass-boost.
Switching between the MUX channels may change the input
signal source or the feedback resistor network. During the
channel switching transition, the average voltage level
20026731
FIGURE 4. Typical Audio Amplifier Application Circuit
(Pin out shown for the 24-pin Exposed-DAP LLP package. Numbers in ( ) are for the 20-pin MTE and MT packages.)
20026728
FIGURE 5. Input MUX Example
L
www.national.com
13
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相關代理商/技術參數 |
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|---|---|
| LM4868MT | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function |
| LM4868MT/NOPB | 功能描述:IC AMP AUDIO PWR 3W AB 20TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負載時最大輸出功率 x 通道數量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風，靜音，短路保護，音量控制 安裝類型:表面貼裝 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4868MTE | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Output-Transient-Free Dual 2.1W Audio Amplifier Plus No Coupling Capacitor Stereo Headphone Function |
| LM4868MTE/NOPB | 功能描述:IC AMP AUDIO PWR 3W AB 20TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:Boomer® 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機，2-通道（立體聲） 在某負載時最大輸出功率 x 通道數量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點:I²C，麥克風，靜音，短路保護，音量控制 安裝類型:表面貼裝 供應商設備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
| LM4869 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:1.9W Differential Input, BTL Output Stereo Audio Amplifier with Selectable Gain and Shutdown |
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