Microphone Diagnostics - Analog Devices EVAL-ADAU1977 User Manual

UG-600
Figure 3. Register Control for the
Figure 4. Register Control for the
ADAU1977 GUI Page 1
ADAU1977 GUI Page 2
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Evaluation Board User Guide
Figure 5. Register Control for the

MICROPHONE DIAGNOSTICS

Microphone diagnostics are applicable for the
used with the microphone input application circuit, as
described in the ADAU1977
1. Connect the microphone to the desired input connector:
J17, J28, J38, or J47.
2. Ensure that the inputs are dc-coupled by setting Switches
S10, S16, S21, and S26 to On.
3. Select the appropriate bias resistors using Switches S7 and
S12 for Channel 1, Switches S15 and S18 for Channel 2,
Switches S20 and S23 for Channel 3, Switches S25 and S29
for Channel 4. The resistor options are 300 Ω or 500 Ω.
4. Select the internal microphone bias by setting Jumpers J22,
J31, J41, J51 to the INT position.
5. Ensure that the Boost Good indicator is green on the GUI
Power Up tab.
6. Ensure Boost is On.
7. By default, the 48 k sample rate is selected, and the boost
switching frequency is 1.5 MHz.
8. In the MIC BIAS CONTROL section, select the desired
microphone bias output voltage (see Figure 3). By default,
it is 8.5 V.
9. Ensure Mic Bias is Enabled (see Figure 3).
10. Check the microphone bias voltage output on the
ADAU1977Z board at the test point (TP).
11. Go to the Diagnostics tab on the GUI (see Figure 5).
12. With the microphone connected, the typical voltage at the
positive (+) input is 2/3 of microphone bias, and at the
negative (−) input is 1/3 of microphone bias.
13. Click Read in the Diagnostics tab on the GUI (see Figure 5).
14. With proper connections and normal working conditions,
all of the channel status indicators will be blue for each
respective channel connected with the microphone.
15. To check the diagnostics functionality, create a fault situation
at the microphone input. This fault situation is done by
ADAU1977 GUI Page 3
ADAU1977
data sheet.
EVAL-
only,