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3.6
EVM Power Tree
The EVM power section is self-contained with all the necessary onboard voltages generated from the
main PVDD (J1) power input. The PVDD is reduced to 15 V and then used to generate the remaining
required board voltages of 12 V, 5 V, and 3.3 V. Low-dropout linear regulators (LDOs) generate supplies
going to the TPA3221 device itself to reduce the chance of extra added noise. LEDs are provided on the
5-V and 3.3-V supplies so that the user can verify that the EVM is powered (see
PVDD
J29
LM5010ASD
3.7
LC Filter Overview
Included near the output of the TPA3251 device are four output LC filters. These output filters filter the
pulse-width modulation (PWM) output, leaving only the audio content at high power, which is fed to the
speakers. The board uses a CoilCraft™ 7-µH inductor and a 0.68-µF film capacitor to form this LC filter.
Using the equations listed in
follows in
Equation
1
F
cut off
2
L C
S
u
Figure 23. BTL LC Frequency Response
3.8
Post-Filter Feedback (PFFB)
The TPA3251EVM has the footprints available to implement post filter feedback to improve the audio
performance of the TPA3251 amplifier. For more details on benefits and implementation, see
and TPA325x Post-Filter Feedback
SLAU751 – November 2017
Submit Documentation Feedback
15 V
J31
LM2940IMP-12
Figure 22. EVM Power Tree
LC Filter Design Application Report
1:
1
2
7 H .68 F
S
P u
P
.
Copyright © 2017, Texas Instruments Incorporated
12 V
J32
TLV117-33IDCY
J36
, the low-pass filter cutoff is calculated as
72.9 kHz
Figure 24. SE LC Frequency Response
Hardware Configuration
Figure
22).
J33
3.3 V
GVDD
TPA324x
TPA3251 Evaluation Module
(1)
13
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