ZHCS767B January 2012 – April 2016 TPA2080D1
PRODUCTION DATA.
Large noise voltages can be present at the output of ΔΣ DACs and CODECs, just above the audio frequency (for example, 80 kHz with a 300 mVP-P). This out-of-band noise is due to the noise shaping of the delta-sigma modulator in the DAC. Some Class-D amplifiers have higher output noise when used in combination with these DACs and CODECs. This is because out-of-band noise from the CODEC/DAC mixes with the Class-D switching frequencies in the audio amplifier input stage. The TPA2080D1 has a built-in low-pass filter with cutoff frequency at 55 kHz that reduces the out-of-band noise and RF noise, filtering out-of-band frequencies that could degrade in-band noise performance. If driving the TPA2080D1 input with 4th-order or higher ΔΣ DACs or CODECs, add an R-C low pass filter at each of the audio inputs (IN+ and IN–) of the TPA2080D1 to ensure best performance. The recommended resistor value is 100 Ω and the capacitor value of 47 nF.