Datasheet

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ANALOG OUTPUTS
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Response (dB)
Frequency (kHz)
PCM1742
SBAS176A – DECEMBER 2000 – REVISED APRIL 2005
The PCM1742 includes two independent output channels: V
OUT
L and V
OUT
R. These are unbalanced outputs,
each capable of driving 3.1 Vp-p typical into a 5-k Ω ac-coupled load. The internal output amplifiers for V
OUT
L and
V
OUT
R are biased to the dc common-mode (or bipolar zero) voltage, equal to V
CC
/2.
The output amplifiers include an RC continuous-time filter that helps to reduce the out-of-band noise energy
present at the DAC outputs, due to the noise shaping characteristics of the PCM1742 delta-sigma DACs. The
frequency response of this filter is shown in Figure 26 . By itself, this filter is not enough to attenuate the
out-of-band noise to an acceptable level for many applications; therefore, an external low-pass filter is required to
provide sufficient out-of-band noise rejection. Further discussion of DAC post-filter circuits is provided in the
Applications Information section of this data sheet.
Figure 26. Output Filter Frequency Response
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