Datasheet

DeviceONBOARD
MICBIAS.GND
MIC.MAIN.P
MICBIAS1.OUT
R
MM.BP
C
MM.B
MIC.MAIN.M
47pF
Closeto
Device
Closeto
Device
037-006
C
MM.P
C
MM.PM
C
MM.M
R /2
MM.GM
C
MM.GM
C
MM.GP
R /2
MM.GM
TPS65930/TPS65920
www.ti.com SWCS037G–MAY 2008–REVISED APRIL 2011
Figure 6-7. Analog Microphone Differential
NOTE
For other component values, see Table 14-1.
NOTE
To improve the rejection, ensure that MICBIAS_GND is as clean as possible. This ground
must be shared with AGND of the TPS65920 or TPS65930 device and must not share with
AVSS4, which is the ground used by RX class AB output stages.
In differential mode, adding a low-pass filter (made by R
SB
and C
B
) is highly recommended if
coupling between RX output stages and the microphone is too high (and not enough
attenuation by the echo cancellation algorithm). The coupling can come from:
• The internal TPS65920/TPS65930 coupling between MICBIAS.OUT voltage and RX
output stages
• Coupling noise between MICBIAS.GND and AVSS4
In pseudodifferential mode, the dynamic resistance of the microphone improves the rejection
versus MICBIAS.OUT:
PSRR = 20*log((R
B
+ R
Dyn_mic
)/R
B
).
6.2.1.2 Silicon Microphone Module Characteristics
Based on silicon micro-electrical-mechanical system (MEMS) technology, the new microphone achieves
the same acoustic and electrical properties as conventional microphones, but is more rugged and exhibits
higher heat resistance. These properties offer designers of a wide range of products greater flexibility and
new opportunities to integrate microphones.
Copyright © 2008–2011, Texas Instruments Incorporated Audio/Voice Module (TPS65930 Device Only) 63
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