CS6422
CS6422
4.1.4.3 Double-talk Attenuation ....................................................................... 36
4.1.4.4 Noise Guard ........................................................................................ 37
4.2 Circuit Design ................................................................................................................... 37
4.2.1 Interface Considerations ..................................................................................... 37
4.2.1.1 Analog Interface .................................................................................. 37
4.2.1.2 Microcontroller Interface ...................................................................... 37
4.2.2 Grounding Considerations .................................................................................. 38
4.2.3 Layout Considerations ........................................................................................ 38
4.3 System Design ................................................................................................................. 38
4.3.1 Gain Structure ..................................................................................................... 38
4.3.2 Testing Issues ..................................................................................................... 39
4.3.2.1 ERLE ................................................................................................... 39
4.3.2.2 Convergence Time .............................................................................. 40
4.3.2.3 Half-Duplex Switching ......................................................................... 40
5. PIN DESCRIPTIONS .............................................................................................................. 41
6. GLOSSARY ............................................................................................................................ 44
7. PACKAGE DIMENSIONS ....................................................................................................... 46
LIST OF FIGURES
Figure 1. CLKI Timing ................................................................................................................... 7
Figure 2. Reset Timing .................................................................................................................. 7
Figure 3. Microcontroller Interface Timing ..................................................................................... 7
Figure 4. Typical Connection Diagram (Microphone Preamplifier Enabled) ................................. 8
Figure 5. Typical Connection Diagram (Microphone Preamplifier Disabled) ................................ 8
Figure 6. Analog Interface ........................................................................................................... 10
Figure 7. Microcontroller Interface .............................................................................................. 12
Figure 8. Suggested Layout ........................................................................................................ 29
Figure 9. Ground Planes ............................................................................................................. 30
Figure 10. Simplified Acoustic Echo Canceller Block Diagram ................................................... 31
Figure 11. How the AGC works (TVol = +30 dB) ........................................................................ 35
LIST OF TABLES
Table 1. Full scale voltages for each gain stage........................................................................... 11
Table 2. MCR Control Register Mapping ...................................................................................... 12
Table 3. Register 0 Bit Definitions................................................................................................. 13
Table 4. Register 1 Bit Definitions................................................................................................. 16
Table 5. Register 2 Bit Definitions................................................................................................. 18
Table 6. Register 3 Bit Definitions................................................................................................. 21
Table 7. Register 4 Bit Definitions................................................................................................. 23
Table 8. Register 5 Bit Definitions................................................................................................. 25
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DS295F1
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