Audio Subsystem - HP Compaq dx6100 Series Technical Reference Manual

Input/Output Interfaces

5.8 Audio Subsystem

A block diagram of the audio subsystem is shown in Figure 5-11. These systems use the AC97
Audio Controller of the 82801 component to access and control an Analog Devices AD1981B
Audio Codec, which provides the analog-to-digital (ADC) and digital-to-analog (DAC)
conversions as well as mixing and equalizer functions. All control functions such as volume,
audio source selection, and sampling rate are controlled through software through the AC97
Audio Controller of the 82801 ICH component. Control data and digital audio streams (record
and playback) are transferred between the Audio Controller and the Audio Codec over the AC97
Link Bus. The codec mono analog output is applied to a single-channel amplifier that drives the
internal speaker. Plugging headphones into the Headphone jack results in an active Spkr Mute
signal used by the codec to ,silence the internal speaker
The analog interfaces allowing connection to external audio devices include:
Mic In—This input uses a three-conductor (stereo) mini-jack that is specifically designed for
connection of a condenser microphone with an impedance of 10-K ohms. This is the default
recording input after a system reset. On systems with both a front and rear microphone jack
either jack is available for use (but not simultaneously).
Line In—This input uses a three-conductor (stereo) mini-jack that is specifically designed for
connection of a high-impedance (10k-ohm) audio source such as a tape deck.
Headphones Out—This input uses a three-conductor (stereo) mini-jack that is designed for
connecting a set of 16-ohm (nom.) stereo headphones or powered speakers. 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) mini-jack for connecting left and right
channel line-level signals (20-K ohm impedance). A typical connection would be to a tape
recorder's Line In (Record In) jacks, an amplifier's Line In jacks, or to powered speakers that
contain amplifiers.
Line In
AUX In Header P11 [1]
CD ROM Header P7 [2]
Mic In
Figure 5-11. Audio Subsystem Functional Block Diagram
5-30
PC Beep Audio
82801 ICH
PCI
AC'97
Bus
AC97
Audio
Link Bus
Cntlr.
(L)
(R)
Aux Audio (L)
Audio
Aux Audio (R)
Codec
CD Audio (L)
CD Audio (R)
P23
Audio
Bias
Mono
Audio TDA
7056
P23
Spkr Mute
HP Out Audio (L/R)
361834-001
Internal
Speaker
P6
+
-
(L)
Headphones/
(R)
Line Out
Technical Reference Guide