NAU8812EVB Nuvoton Technology Corporation of America, NAU8812EVB Datasheet - Page 22

• Manufacturer Part Number: NAU8812EVB
• Description: BOARD EVAL FOR NAU8812
• Manufacturer: Nuvoton Technology Corporation of America
• Series: emPowerAudio™r

Specifications of NAU8812EVB

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MICBIAS pin is a low-noise microphone bias source for an external microphone, which can provide a maximum
of 3mA of bias current.
microphones, or for MEMS types microphones with an independent power supply pin. Seven different bias voltages
are available for optimum system performance, depending on the specific application. The microphone bias pin
normally requires an external filtering capacitor as shown on the schematic in the Application section.
The output bias can be enabled by setting MICBIASEN[4] address (0x01) to HIGH. It has various voltage values
selected by a combination of bits MICBIASM[4] address (0x3A) and MICBIASV[8:7] address (0x2C).
The low-noise feature results in greatly reduced noise in the external MICBIAS voltage by placing a resistor of
approximately 200-ohms in series with the output pin. This creates a low pass filter in conjunction with the external
microphone-bias filter capacitor, but without any additional external components.
Below are the unloaded values when MICBIASM[4] is set to 1 and 0. When loaded, the series resistor will cause the
voltage to drop, depending on the load current.
emPowerAudio
Datasheet Revision 2.0
12.2.
MICBIASV[8:7]
MICBIASEN[4]
MICBIASM[4]
Bit(s)
MICROPHONE BIASING
™
VREF
(0x2C)
(0x3A)
This DC bias voltage is suitable for powering either traditional ECM (electret) type
Addr
0x01
Table 7: Register associated with Microphone Bias
Microphone bias enable
Microphone bias mode selection
Microphone bias voltage selection
Figure 8: Microphone Bias Schematic
Page 22 of 109
MICBIASM[0]
(0x28)
Parameter
R
R
MICBIASV[1:0]
(0x2C)
0 = Disable
1 = Enable
0 = Disable
1 = Enable
MICBIAS
Programmable Range
NAU8812
January 2011