NAU8812EVB Nuvoton Technology Corporation of America, NAU8812EVB Datasheet - Page 35

• 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

de-emphasis feature is included to accommodate audio recordings that utilize 50/15 s pre-emphasis equalization as
a means of noise reduction. The DAC output can be inverted (phase inversion) by setting DACPL[1:0] address
(0x0A) to HIGH, non-inverted output is set by default.
Output Peak-Limiters reduce the dynamic range by ensuring the signal will not exceed a certain threshold, while
maximizing the RMS of the resulted audio signal, and minimizing audible distortions. NAU8812 has a digital output
limiter function. In the figure below, the upper graph shows the envelope of the input/output signals and the lower
graph shows the gain characteristic. The limiter has a programmable threshold, DACLIMTHL[6:4] address (0x19),
which ranges from -1dB to -6dB in 1dB increments. The digital peak limiter seeks to keep the envelope of the output
signal within the target threshold +/- 0.5dB. The attack and decay rates programmed in registers DACLIMATK[3:0]
address (0x18) and DACLIMDCY[7:4] address (0x18) specify how fast the digital peak limiter decrease and increase
the gain, respectively, in response to the envelope of the output signal falling outside of this range. In normal
operation LIMBST=000 signals below this threshold are unaffected by the limiter.
The limiter has programmable upper gain, which boosts signals below the threshold to compress the dynamic range
of the signal and increase its perceived loudness. This operates as an ALC function with limited boost capability.
The volume boost is from 0dB to +12dB in 1dB steps, controlled by the DACLIMBST[3:0] register bits. The output
limiter volume boost can also be used as a stand-alone digital gain boost when the limiter is disabled.
emPowerAudio
Datasheet Revision 2.0
12.5.5. Digital DAC Output Peak Limiter
12.5.6. Volume Boost
™
DAC Output
Digital Gain
DAC Input
Signal
Data
Figure 18: DAC Digital Limiter Control
Page 35 of 109
Threshold
-1dB
-1dB
-0.5dB
0dB
NAU8812
January 2011