Datasheet


SLES071B − MARCH 2003 − REVISED NOVEMBER 2006
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55
V
DD
Digital Section Analog Section
RF Choke or Ferrite Bead
Power Supplies
Common
Ground
Output
Circuits
AGND
V
CC
+V
S
+5V −V
S
AGND
V
DD
DGND
REG
PCM1791A
Figure 65. Single-Supply PCB Layout
Bypass and Decoupling Capacitor Requirements
Various sized decoupling capacitors can be used, with no special tolerances being required. All capacitors must be
located as close as possible to the appropriate pins of the PCM1791A to reduce noise pickup from surrounding
circuitry. Aluminum electrolytic capacitors that are designed for hi-fi audio applications are recommended for larger
values, while metal film or monolithic ceramic capacitors are used for smaller values.
Post-LPF Design
By proper choice of the operational amplifier and resistors used in the post-LPF circuit, excellent performance of the
PCM1791A should be achieved. To obtain 0.001% THD+N and 113 dB signal-to-noise-ratio audio performance, the
THD+N and input noise performance of the operational amplifier should be considered. This is because the input
noise of the operational amplifier contributes directly to the output noise level of the application. The V
OUT
pin of the
PCM1791A and the input resistor of the post-LPF circuit must be connected as closely as possible.
Out-of-band noise level and attenuated sampling spectrum level are much lower than for typical delta-sigma type
DACs due to the combination of a high-performance digital filter and advanced segment DAC architecture. The use
of a second-order or third-order post-LPF is recommended for the post-LPF of the PCM1791A. The cutoff frequency
of the post-LPF depends on the application. For example, there are many sampling-rate operations such as f
S
= 44.1
kHz on CDDA, f
S
= 96 kHz on DVD-M, f
S
= 192 kHz on DVD-A, f
S
= 64 f
S
on DSD (SACD).