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參數(shù)資料
| 型號： | LM4841 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive |
| 中文描述： | 2W的立體聲放大器直流音量控制，瞬態(tài)自由輸出，無電容耳機驅(qū)動器 |
| 文件頁數(shù)： | 18/31頁 |
| 文件大?。?/td> | 1138K |
| 代理商： | LM4841 |
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Application Information
(Continued)
BEEP DETECT FUNCTION
Computers and notebooks produce a system “beep“ signal
that drives a small speaker. The speaker’s auditory output
signifies that the system requires user attention or input. To
accommodate this system alert signal, the LM4841’s beep
input pin is a mono input that accepts the beep signal.
Internal level detection circuitry at this input monitors the
beep signal’s magnitude. When a signal level greater than
V
/2 is detected on the BEEP IN pin, the bridge output
amplifiers are enabled. The beep signal is amplified and
applied to the load connected to the output amplifiers.Avalid
beep signal will be applied to the load even when MUTE is
active. Use the input resistors connected between the BEEP
IN pin and the stereo input pins to accommodate different
beep signal amplitudes. These resistors are shown as
200k
devices in
Figure 2
. Use higher value resistors to
reduce the gain applied to the beep signal. The resistors
must be used to pass the beep signal to the stereo inputs.
The BEEP IN pin is used only to detect the beep signal’s
magnitude: it does not pass the signal to the output amplifi-
ers. The LM4841’s shutdown mode must be deactivated
before a system alert signal is applied to BEEP IN pin.
MICRO-POWER SHUTDOWN
The voltage applied to the SHUTDOWN pin controls the
LM4841’s shutdown function. Activate micro-power shut-
down by applying ground (logic low) to the SHUTDOWN pin.
When activated, the LM4841’s micro-power shutdown fea-
ture turns off the amplifier’s bias circuitry, reducing the sup-
ply current. On the demo board, the micro-power shutdown
feature is controlled by a single pole switch that connects the
shutdown pin to either V
, for normal operation, or directly
to ground to enable shutdown. In a system with a micropro-
cessor or a microcontroller, use a digital output to apply the
control voltage to the SHUTDOWN pin.
MODE FUNCTION
The LM4841’s MODE function has 2 states controlled by the
voltage applied to the MODE pin. In Mode 0 (mode pin at
GND), the HP Sense has no effect on the gain setting (only
the Gain Select Input Controls either internal or external
gain). In Mode 1 (mode pin tied high), the HP Sense and
Gain Select both can toggle between Internal and External
Gain. See ’Truth Table for Logic Inputs’ on page 5.
MUTE FUNCTION
The LM4841 mutes the amplifier and DOCK outputs when
V
is applied to the MUTE pin. Even while muted, the
LM4841 will amplify a system alert (beep) signal whose
magnitude satisfies the BEEP DETECT circuitry. Applying
0V to the MUTE pin returns the LM4841 to normal, unmuted
operation. Prevent unanticipated mute behavior by connect-
ing the MUTE pin to V
DD
or ground. Do not let the mute pin
float.
20028087
FIGURE 5. Headphone Sensing Circuit (MT & MH Packages)
L
www.national.com
18
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM4841LQ | Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive |
| LM4841MH | Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive |
| LM4841MT | Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive |
| LM4842 | Stereo 2W Amplifiers with DC Volume Control Transient Free Outputs, and Cap-less Headphone Drive |
| LM4842LQ | Stereo 2W Amplifiers with DC Volume Control Transient Free Outputs, and Cap-less Headphone Drive |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM48410 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Low EMI, Filterless, 2.3W Stereo Class D Audio Power Amplifier with National 3D Enhancement |
| LM48410SQ | 制造商:Texas Instruments 功能描述:Audio Amp Speaker 2-CH Stereo 2.3W Class-D 24-Pin LLP EP T/R 制造商:Texas Instruments 功能描述:AMP, POWER, CLASS D, 2.3W, LLP-24 |
| LM48410SQ/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| LM48410SQBD | 功能描述:音頻 IC 開發(fā)工具 LM48410 EVAL BOARD RoHS:否 制造商:Texas Instruments 產(chǎn)品:Evaluation Kits 類型:Audio Amplifiers 工具用于評估:TAS5614L 工作電源電壓:12 V to 38 V |
| LM48410SQE/NOPB | 功能描述:音頻放大器 RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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