adau1373 Analog Devices, Inc., adau1373 Datasheet - Page 40

• Manufacturer Part Number: adau1373
• Description: Low Power Codec With Speaker And Headphone Amplifier Adau1373
• Manufacturer: Analog Devices, Inc.

ADAU1373
Microphone Bias
The MICBIAS1 and MICBIAS2 pins (Ball C8 and Ball C9,
respectively) provide a voltage reference for electret analog
microphones. These pins are independent MICBIASx voltage
outputs that can be set using Register 0x21 to Register 0x23 of
the I
Register 0x21. Four output voltage settings are available: 1.8 V,
2.2 V, 2.6 V, and 2.9 V.
Current sense circuits can detect the current going out of the
MICBIAS1 pin or MICBIAS2 pin. This current detect function
can be used to sense the presence of the electret microphone. The
internally generated current sense logic output can be used as an
interrupt on any of the four GPIOs to communicate to the system
controller. The current sense can be enabled or disabled using
Register 0x22 for MICBIAS1 and Register 0x23 for MICBIAS2.
Additional options include overcurrent protection, which can be
used to sense the short circuit of MICBIAS1 or MICBIAS2 to
ground at the microphone inputs. The overcurrent threshold is
programmable, allowing for flexibility in system design.
The MICBIASx pins can also be used to supply voltage to digital
microphones or analog microphones with separate power supply
pins. However, the maximum current that is available from the
MICBIAS1 or MICBIAS2 pin is 1.8 mA.
Microphone Input Connection
To use the microphone input, first identify the type of microphone
being used. The ADAU1373 provides microphone bias for
condenser microphones. Set the bias voltage as required in the
application. It is recommended that the bias be connected to the
desired microphone input using a 2 kΩ resistor.
If using a single-ended condenser microphone, see Figure 83 for
the correct connection configuration.
MICROPHONE
MICROPHONE
2
C control registers. The MICBIASx voltage can be set via
Figure 83. Condenser Microphone Input, Single-Ended
RIGHT
LEFT
2kΩ
2kΩ
AINxR/AINxN
AINxL/AINxP
MICBIASx
–12dB TO
+18dB
–12dB TO
+18dB
RIGHT
PGA MODE
ADAU1373
PGA
Rev. 0 | Page 40 of 296
If using a differential or balanced condenser microphone
configuration, see Figure 84.
Line Input Connection
To use the analog input as the line input, configure the input to
either stereo (single-ended) or mono (differential), as desired
(see Figure 85 or Figure 86, respectively).
MICROPHONE
MICROPHONE
*R1 AND R2 CAN BE 2k Ω FOR DIFFERENTIAL OR 0Ω FOR
PSEUDO-DIFFERENTIAL INPUT.
RIGHT LINE
LEFT LINE
+INPUT
–INPUT
Figure 84. Condenser Microphone Input, Differential
INPUT
INPUT
RIGHT
LEFT
2kΩ
2kΩ
R1*
R2*
Figure 85. Single-Ended Line Input
Figure 86. Differential Line Input
AINxR/AINxN
AINxL/AINxP
AINxR/AINxN
AINxL/AINxP
AINxR/AINxN
AINxR/AINxP
AINxL/AINxP
AINxL/AINxN
MICBIASx
ADAU1373
–12dB TO
+18dB
–12dB TO
+18dB
ADAU1373
–12dB TO
+18dB
–12dB TO
+18dB
–12dB TO
+18dB
ADAU1373
PGA MODE
PGA MODE