Texas Instruments TPA3223EVM, User Manual, Page: 13 / 33

cut off
1 1
50.3 kHz
2 L C 2 10 H 1 F
-
= = =
p ´ p m ´ m
F
(2)
The frequency response of the filter per output load is illustrated in Figure 3-1 .
6 Ÿ
3 Ÿ
4 Ÿ
2 Ÿ
8 Ÿ
Figure 3-1. Filter Frequency Response
Figure 3-1 is taken directly from the LC Filter Calculator tool available on TI.com ( SLAC729 ). The tool is
configured for BTL common mode with values of 10 µH and 1 µF for the filter. This tool is also helpful when
designing a different board featuring one of TI’s class-D amplifiers.
The Sagami inductor used (7G14D-100M-R) has a saturation current of 15 A. This was selected for the EVM
since the TPA3223 supports a maximum short-circuit output current of 9 A. The inductance versus current curve
for a selected inductor is very important. It is essential for the inductor to maintain at least 5 µH of inductance
at the maximum short-circuit current of the power amplifier. The Sagami inductance versus current curve is
available in the 7G14D-100M-R data sheet on the Sagami web site.
Although not required, shielded inductors are used on the EVM to reduce EMI.
3.8 Reset Circuit and POR
The TPA3223EVM includes RESET supervision so that the TPA3223 device remains in reset until all power rails
are up and stable. The RESET supervisor also maintains that the device is put into reset if one of the power rails
experiences a brown out. This circuit combined with the RESET switch (S1) helps make sure that the TPA3223
can be placed in reset easily, as needed, or automatically if there is a power supply issue.
Figure 3-2 illustrates
the circuit.
www.ti.com Hardware Configuration
SLAU874 – OCTOBER 2022
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TPA3223 Evaluation Module 13
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