AD1953 Analog Devices, AD1953 Datasheet - Page 32

• Manufacturer Part Number: AD1953
• Description: SigmaDSP Digital Audio Processor
• Manufacturer: Analog Devices

AD1953
The sub output of the AD1953 has a lower drive strength than
the left and right output pins (± 0.25 mA peak versus ± 0.5 mA
peak for the left and right outputs). For this reason, it is best to
use higher resistor values in the external sub filter. Figure 24
shows a recommended filter design for the subwoofer output
pins used as a full-bandwidth channel in a custom-designed
program. This design is also a 100 kHz Bessel filter.
For best performance, a large (> 10 µF) capacitor should be
connected between the FILTCAP pin and analog ground. This
pin is connected to an internal node in the bias generator, and
by adding an external capacitance to this pin, the thermal noise
of the left/right channels is minimized. The sub channel is not
affected by this connection.
Figure 22. Recommended External Analog Filter for
Main Channels
+ INPUT
– INPUT
2.80k
806
2.7nF
1nF
1.50k
1.00k
3.01k
499
270pF
820pF
549
2.2nF
OUT
–32–
GRAPHICAL CUSTOM PROGRAMMING TOOLS
Custom programming tools are available for the AD1953 from
ADI. These graphical tools allow the user to modify the default
signal processing flow by individually placing each block (e.g.,
biquad filter, Phat Stereo, dynamics processor) and connecting
them in any desired fashion. The program then creates a file
that is loaded into the AD1953’s program RAM. All of the
contents of the parameter RAM can also be set using these
tools. For more information on these programming tools, email
[e-mail].
Figure 23. Recommended External Analog Filter for
Sub Channel
Figure 24. Recommended External Analog Filter for Full
Bandwidth Signals on the Sub Channel Output
– INPUT
+ INPUT
– INPUT
+ INPUT
5.62k
5.62k
11k
11k
270nF
560nF
5.62k
5.62k
11k
11k
27nF
56nF
3.01k
3.01k
27nF
56nF
1.5k
1.5k
6.8nF
15nF
150pF
150pF
68pF
68pF
220nF
604
604
2.2nF
2.2nF
REV. 0
OUT
OUT