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Technical Reference Guide www.hp.com 5-13
Input/Output Interfaces
5.8 Audio Subsystem
These systems use the HD audio controller of the 82801 component to access and control an
Analog Devices AD1884A HD Audio Codec, which provides 2-channel high definition
analog-to-digital (ADC) and digital-to-analog (DAC) conversions. A block diagram of the audio
subsystem is shown in Figure 5-9. All control functions such as volume, audio source selection,
and sampling rate are controlled through software through the HD Audio Interface of the 82801
ICH component. Control data and digital audio streams (record and playback) are transferred
between the ICH and the Audio Codec over the HD Audio Interface. The codec’s speaker output
is applied to a 1.5-watt amplifier that drives the internal speaker. A device plugged into the
Headphone jack or the line input jack is sensed by the system, which will inhibit the Speaker
Audio signal.
These systems provide the following analog interfaces for external audio devices:
Microphone In—This input uses a three-conductor 1/8-inch mini-jack that accepts a stereo
microphone.
Line In—This input uses a three-conductor (stereo) 1/8-inch mini-jack designed for connection
of a high-impedance audio source such as a tape deck. This jack can be re-tasked to a
Microphone In function.
Headphones Out—This input uses a three-conductor (stereo) 1/8-inch mini-jack that is
designed for connecting a set of 32-ohm (nom.) stereo headphones. Plugging into the
Headphones jack mutes the signal to the internal speaker and the Line Out jack as well.
Line Out—This output uses a three-conductor (stereo) 1/8-inch mini-jack for connecting left
and right channel line-level signals. Typical connections include a tape recorder's Line In
(Record In) jacks, an amplifier's Line In jacks, or to powered speakers that contain amplifiers.
Figure 5-9. Audio Subsystem Functional Block Diagram
82801 ICH
HD Audio
Interface
Headphone
Mic In
Audio (L/R)
HD Audio
Codec
AD1884A
Speaker
Audio (mono)
Header
Header
Rear Panel
NOTES:
L/R = Separate left and right channels (stereo). L+R = Combined left and right channels (mono).
P23
P6
Audio
Amp
HD Audio I/F
Front Panel
Line In [1]
Headphones Out
Front Panel
Mic Audio (L/R)
[1] Can be re-configured as Microphone In
PC Beep
Header
P23
Out (L/R)
Line Audio
Line Out
Line Audio (L/R)
Rear Panel