
D6571E Data Sheet
DS6571E.2
DSP GROUP, INC., 3120 SCOTT BOULEVARD
SANTA CLARA, CA 95054 PH: 408 986-4300 FAX: 408 986-4490
106
APPLICATION HINTS
A good printed circuit board (PCB) layout is as important
as the overall circuit design itself in achieving high audio
quality. To achieve this, the designer has to be conscious
of noise both in the D6571E chip and the front-end analog
circuitry. Switching mode power supplies are not
recommended as the switching spikes will feed through.
Other causes of concern are ground loops and digital feed
through.
Layout Hints
Ensure that the layout for the printed circuit board has
digital and analog signal lines separated as much as
possible. Take care not to run any digital track along side
an analog signal. Guard the analog input with AGND.
Establish a single point analog ground separate from the
digital ground. Low impedance analog and digital power
supply common returns are essential to low noise
operation.
Power Supply Considerations
Since the D6571E is a chipset with analog input and
output, its performance (especially the analog front-end)
may be adversely affected by the noise of the power
supply. In order to prevent mixing of noise, observe the
following cautions:
Separate the power supply to the digital parts and
analog parts.
GNDs of two power supplies should be connected at
only one point. Furthermore, that connecting point
should be close to the supplies. This will minimize the
effect of noise from the digital power supply to the
analog power supply.
The power supply should have the least ripple possible,
and a series regulator power supply is recommended for
best operation.
Good engineering practice calls for proper supply
decoupling between the various components. This may
be achieved by running separate VCC and ground lines to
the D6571E and Flash memory and placing 0.1
μ
F ceramic
decoupling capacitors near each V
CC
supply pin.
Microphone and Speaker Considerations
An often overlooked fact is that the sound quality
produced by D6571E chipset is directly related to the
quality of the microphone and speaker connected to them.
Use a good quality microphone and speaker with good
frequency response. Carefully design the microphone
preamplifier circuit. The physical location of the
microphone, along with the characteristics of the
microphone, play a large role in the playback sound
quality.
0.1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
10
μ
F
10
μ
F
33
μ
F
33
μ
F
POWER
SUPPLY
D6571E
PCB
VCCA (+ 5V, analog)
VBBA (-5V, analog)
VCC (digital)
VCC1 (digital)
GNDD (digital)
GNDA (analog)
Figure 10. Power Supply