NAU8812EVB Nuvoton Technology Corporation of America, NAU8812EVB Datasheet - Page 29

• 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

Normal mode is selected when ALCM[8] address (0x22) is set LOW and the ALC is enabled by setting ALCEN[8]
address (0x20) HIGH. This block adjusts the PGA gain setting up and down in response to the input level. A peak
detector circuit measures the envelope of the input signal and compares it to the target level set by ALCSL[3:0]
address (0x21). The ALC increases the gain when the measured envelope is greater than the target and decreases
the gain when the measured envelope is less than - 1.5dB. The following waveform illustrates the behavior of the
ALC.
The hold parameter ALCHT[3:0] configures the time between detection of the input signal envelope being outside of
the target range and the actual gain increase.
Input signals with different characteristics (e.g., voice vs. music) may require different settings for this parameter for
optimal performance. Increasing the ALC hold time prevents the ALC from reacting too quickly to brief periods of
silence such as those that may appear in music recordings; having a shorter hold time, on the other hand, may be
useful in voice applications where a faster reaction time helps to adjust the volume setting for speakers with different
volumes. The waveform below shows the operation of the ALCHT parameter.
emPowerAudio
Datasheet Revision 2.0
PGA Output
12.4.1.1.
PGA Input
12.4.1.2.
PGA Gain
™
Normal Mode
ALC Hold Time (Normal mode Only)
Figure 12: ALC Normal Mode Operation
Page 29 of 109
NAU8812
January 2011