VIPER Technical Manual | Detailed hardware description |
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Audio
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A National Semiconductor LM4549 AC’97 audio CODEC is used to support the audio features of the VIPER. Audio inputs supported by the LM4549 are stereo line in and a mono microphone input.
The LM4549 provides a stereo line out that can also be amplified by a National Semiconductor LM4880 250mW per channel power amplifier, suitable for driving an 8Ω load. The LM4549 AC’97 codec may be turned off if it is not required. See the section
Audio357Hpower management, page 8435 H, for details.
Connection to the VIPER audio features is via header PL6. See the table below for pin assignments and the section PL6359H– Audio connector, page 91360H, for connector and mating connector details.
Function | Pin | Signal | Signal levels (max) | Frequency | |
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| 10 | MIC input |
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Microphone | 9 | MIC voltage reference output | 1Vrms | 20 – 20k | |
| 7 | Audio ground reference. |
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| 1 | Line input left |
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Line in | 5 | Line input right | 1Vrms | 20 – 20k | |
| 3 | Audio ground reference |
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| 2 | Line output left |
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Line out | 6 | Line output right | 1Vrms | 20 – 20k | |
| 4 | Audio ground reference |
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| 8 | Amp output left | 1.79V peak , | 20 – 20k | |
Amp out | 11 | Amp output right | 1.26Vrms | ||
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| 12 | Audio ground reference | (8Ω load) 223mW |
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The left and right amp output signals are not AC coupled, these signals must be AC coupled with 100uF capacitors externally.
© 2007 Eurotech Ltd Issue E | 56 |