LM4857

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(The audio amplifier in the neo,.)
 
 
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An audio power amplifier, connected to the 3.3V power supply.
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* Feature: Stereo Amplifier
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* Product Homepage: [http://www.national.com/pf/LM/LM4857.html LM4857.html]
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* Data Sheet: [http://www.national.com/ds.cgi/LM/LM4857.pdf LM4857.pdf]
  
* 0.5W stereo speaker output, used for the main speakers.
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== Neo 1973 ==
* 33mW stereo headphone output (32 ohms), for the headphones.
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{{Main|Neo_1973_hardware}}
* 43mW mono earpiece output, for the earpiece.
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* Connects to: [[Samsung S3C2410]] I2C (Control)
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* Connects to: The stereo (LIN and RIN) input is connected to [[WM8753]]
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* Not used: The mono (MIN) input
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The '''LM4857''' is an audio power amplifier and part of the [[Neo1973 audio subsystem]]. It's connected to the VB power rail (battery terminal voltage) for power and thus needs to be powered off separately from the main system.
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The audio power output may vary as the battery discharges:
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* 0.5W per-channel stereo speaker output, used for the main speakers (LLS+- and RLS+-)
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* 33mW per-channel stereo headphone output (32 ohms), for the headset (LHP and RHP)
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* 43mW mono earpiece output, for the earpiece (EP+-)
 
* Line-out, unused.
 
* Line-out, unused.
  
[http://www.national.com/pf/LM/LM4857.html Datasheet.]
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Mixer settings starting "Amp" control it via [[I2C]], including:
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* Amp Mode: Off (mode 0), Call Speaker (mode 6), Stereo Speakers (mode 7), Stereo Speakers + Headphones (mode 8), Headphones (mode 9)
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* The volume controls Amp Left and Amp Right, and Amp Mono
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* Amp Earpiece 6dB toggle amplifies the call speaker output
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[[Category:Neo1973 Hardware]]
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[[Category:Audio]]

Latest revision as of 12:11, 18 August 2008

[edit] Neo 1973

Main article: Neo_1973_hardware


  • Connects to: Samsung S3C2410 I2C (Control)
  • Connects to: The stereo (LIN and RIN) input is connected to WM8753
  • Not used: The mono (MIN) input

The LM4857 is an audio power amplifier and part of the Neo1973 audio subsystem. It's connected to the VB power rail (battery terminal voltage) for power and thus needs to be powered off separately from the main system.

The audio power output may vary as the battery discharges:

  • 0.5W per-channel stereo speaker output, used for the main speakers (LLS+- and RLS+-)
  • 33mW per-channel stereo headphone output (32 ohms), for the headset (LHP and RHP)
  • 43mW mono earpiece output, for the earpiece (EP+-)
  • Line-out, unused.

Mixer settings starting "Amp" control it via I2C, including:

  • Amp Mode: Off (mode 0), Call Speaker (mode 6), Stereo Speakers (mode 7), Stereo Speakers + Headphones (mode 8), Headphones (mode 9)
  • The volume controls Amp Left and Amp Right, and Amp Mono
  • Amp Earpiece 6dB toggle amplifies the call speaker output
Personal tools

An audio power amplifier, connected to the 3.3V power supply.

  • 0.5W stereo speaker output, used for the main speakers.
  • 33mW stereo headphone output (32 ohms), for the headphones.
  • 43mW mono earpiece output, for the earpiece.
  • Line-out, unused.

Datasheet.