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3.3 Modulation Modes (AD Mode and HEAD Mode)
The TPA3223EVM supports both AD modulation as well as HEAD modulation. In AD mode, each of the two
half-bridge outputs are continuously switching. AD mode is the default mode for the TPA3223EVM. The EVM
also supports HEAD mode modulation. HEAD mode also switches both half bridge outputs but also optimizes
the switching for lower power loss at idle as well as increased EMI performance at cost of some performance.
The device accomplishes this by reducing its duty cycle at idle and while playing small signals. At higher output
levels HEAD mode will also reduce the switching on one of the half bridges. The modulation mode can be
controlled through jumper J6 on the EVM as follows:
More information on the differences between HEAD mode and AD mode as well as performance data is found in
the TPA3223 data sheet (SLASEF0).
3.4 Output Mode Selection
The TPA3223 does not use discrete mode pins and therefore relies solely on the states of the IN2_M and IN2_P
pins. Connecting the IN2_M and IN2_P pins to regular high output impedance audio outputs by removing J7
and J8 puts the TPA3223 into BTL mode (2 x stereo outputs). Tying the IN2_M and IN2_P pins to GND by
installing J7 and J8 on pins 2-3 puts the TPA3223 into PBTL mode (1 x mono output). Tying the IN2_M and
IN2_P pins to 5V by installing J7 and J8 on pins 1-2 puts the TPA3223 into 1x BTL mode (1 x mono output). This
is summarized in
Table
3-4:
Input Jumpers J7
and J8
Input Mode
IN2_M
IN2_P
OUT
OUT
2-3
2-3
1N / 2N + 1
(GND)
(GND)
1-2 (5V) 1-2 (5V)
3.5 Audio Front End
The TPA3223EVM includes options for single-ended or differential input signals. A configurable front end is
built into the TPA3223 so that both single-ended and differential inputs can achieve the full scale output of the
TPA3223 device without need for external front end op-amp. Note that when EVM RCA or XLR connectors are
used, jumpers J11, J10, J21, and J20 must be installed in position 1:2 named XLR or RCA.
•
Single-ended input can be provided through RCA to inputs J3 and J18. Uninstall jumpers J4 and J12 using
SE input so that the TPA3223 front-end will be configured for SE input.
•
Differential input can be provided through XLR to inputs J14 and J15. Install jumpers J4 and J12 when using
DIFF input so that the TPA3223 front-end will be configured for DIFF input.
Input can also be provided through an audio plug-in board on J28. For this input type, change jumpers J11, J10,
J21, and J20 to position 2:3 named AIB.
See the EVM schematic section
SLAU874 – OCTOBER 2022
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Table 3-3. HEAD and AD Mode Selection
J6 Jumper State
IN
OUT
Table 3-4. Output Mode and Modulation Mode Selection
Output
Description
Configuration
2 × BTL
Stereo, BTL output configuration
Mono, Paralleled BTL configuration. Connect OUT1+ to OUT2+ and
1 × PBTL
OUT1– to OUT2–
1 × BTL
Mono, BTL configuration. OUT1+ and OUT1– active
(Section
1.4.3) for complete details.
Copyright © 2022 Texas Instruments Incorporated
Modulation Mode
AD Mode
HEAD Mode
Hardware Configuration
TPA3223 Evaluation Module
11
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