www.ti.com
Hardware Configuration
7
SLAU756–January 2018
Submit Documentation Feedback Copyright © 2018, Texas Instruments Incorporated
TPA3220 Evaluation Module Micro
ADVANCE INFORMATION
3 Hardware Configuration
3.1 Indicator Overview (CLIP_OTW and FAULT)
The TPA3220EVM-Micro is equipped with LED indicators that illuminate when the FAULT or CLIP_OTW
pin goes low. See Table 3 and TPA3220 100-W Peak HD-Audio, Analog-Input, Class-D for more details.
Table 3. Fault and Clip Overtemperature Status
FAULT LED
Status CLIP_OTW LED Status Description
ON ON Overtemperature (OTE) or overload (OLP) or undervoltage (UVP). Junction
temperature higher than 125°C (OTE warning)
ON OFF Overload (OLP) or undervoltage (UVP). Junction temperature lower than 125°C
OFF ON Junction temperature higher than 125°C (OTE warning)
OFF OFF Junction temperature lower than 125°C and no OLP or UVP faults (normal
operation)
3.2 PWM Frequency Adjust
The TPA3220EVM-Micro allows for three oscillator frequency options by external configuration of the
FREQ_ADJ pin. The frequency adjust can be used to reduce interference problems while using a radio
receiver tuned within the AM band. These values should be chosen such that the nominal and the lower
value switching frequencies together results in the fewest cases of interference throughout the AM band.
The oscillator frequency can be selected by the value of the FREQ_ADJ resistor connected to GND in
master mode according to Table 4.
Table 4. Frequency Adjust Master Mode Selection
FREQ_ADJ (R25, R) Resistor Value PWM Frequency
Master MODE 49.9 kΩ600 kHz
Master MODE 30 kΩ533 kHz
Master MODE 10 kΩ480 kHz
Slave MODE Pull up to 5 V N/A
Selecting Slave Mode configures the OSC_I/O pins as inputs to be slaved from an external differential
clock. In a master or slave system, interchannel delay is automatically set up between the switching
phases of the audio channels, which can be illustrated by no idle channels switching at the same time.
This will not influence the audio output, but only the switch timing to minimize noise coupling between
audio channels through the power supply. This will optimize audio performance and result in better
operating conditions for the power supply. The inter-channel delay will be set up for a slave device
depending on the polarity of the OSC_I/O connection such that slave mode 1 is selected by connecting
the OSC_I/O of the master device with the OSC_I/O of the slave device with the same polarity (+ to +
and – to –), while slave mode 2 is selected by connecting the OSC_I/Os with the inverse polarity (+ to –
and – to +).
3.3 Modulation Modes (AD Mode and HEAD Mode)
The TPA3220EVM-Micro 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
TPA3220EVM-Micro. 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:
