NAU8812EVB Nuvoton Technology Corporation of America, NAU8812EVB Datasheet - Page 19

• 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 positive microphone input (MIC+) can be used as part of the differential input. It connects to the positive terminal
of the PGA gain amplifier by setting PMICPGA[0] address (0x2C) to HIGH or can be connected to VREF by setting
PMICPGA[0] address (0x2C) to LOW.
When the associated control bit is set logic = 1, the MIC+ pin is connected to a resistor of approximately 1kΩ which is
tied to VREF. The purpose of the tie to VREF is to reduce any pop or click sound by keeping the DC level of the
MIC+ pin close to VREF at all times.
Note: In single ended applications where the MIC+ input is used without using MIC-, the PGA gain values will be
valid only if the MIC- pin is terminated to a low impedance signal point. This termination should normally be an AC
coupled path to signal ground. This input impedance is constant regardless of the gain value. The following table
gives the nominal input impedance for this input. Impedance for specific gain values not listed in this table can be
estimated through interpolation between listed values.
The negative microphone input (MIC-) has two distinctive configuration; differential input or single ended input. This
input connects to the negative terminal of the PGA gain amplifier by setting NMICPGA[1] address (0x2C) to HIGH.
When the MIC- is used as a single ended input, MIC+ should be conned to VREF by setting PMICPGA[0] address
(0x2C) bit to LOW. The AUX input signal can also be mixed with the MIC- input signal by setting AUXPGA[2]
address (0x2C) to HIGH.
emPowerAudio
Datasheet Revision 2.0
12.1.2.2.
Table 3: Microphone Non-Inverting
12.1.2.1.
™
MIC+ to non-inverting PGA input
Gain (dB)
Nominal Input Impedance
35.25
Negative Microphone Input (MIC-)
-12
12
18
30
-9
-6
-3
0
3
6
9
Input Impedances
Positive Microphone Input (MIC+)
Impedance (kΩ)
94
94
94
94
94
94
94
94
94
94
94
94
Page 19 of 109
Table 4: Microphone Inverting Input
Gain (dB)
MIC- to inverting PGA input
Nominal Input Impedance
35.25
-12
12
18
30
-9
-6
-3
0
3
6
9
Impedances
Impedance (kΩ)
2.9
1.6
75
69
63
55
47
39
31
25
19
11
NAU8812
January 2011