Customizing the EVM
3
Customizing the EVM
The TPA6120A2RGY EVM comes in a differential configuration with a gain of 1 V/V. However, the EVM is
designed to be flexible, and can be converted to operate in single-ended inverting and noninverting
configurations. The TPA6120A2RGY EVM can also be operated in a single power supply configuration.
3.1
Single-Ended Inverting Configuration
The TPA6120A2RGY EVM can operate in a single-ended inverting gain configuration without modification.
To operate in single-ended mode with the unmodified EVM, simply put the signal line into the inverting
terminal (–) and the ground line into the noninverting terminal (+). This yields an inverting configuration
with a gain of –1 V/V.
The EVM can also be modified to operate in single-ended inverting only mode with a reduced BOM. To do
this, short resistors R1, R2, R9 (for the left channel) and short R10, R11, and R12 (for the right channel).
Put the signal line on the inverting terminal and the ground line on the noninverting terminal. This yields an
inverting configuration with a gain of –1 V/V.
3.2
Single-Ended Noninverting Configuration
The EVM can operate in a single-ended noninverting gain configuration without modification by applying
the signal line to the noninverting input and the ground line to the inverting input. This yields a gain of +1
V/V.
Another possible setup for noninverting configuration is to remove R9 (for the left channel) and R10 (for
the right channel). Apply the signal line to the noninverting input and the ground line to the inverting input.
This yields a gain of +2 V/V.
3.3
Special Note on Filtering and Capacitors C7 and C8
Capacitors C7 and C8 can be added into the EVM to form a low-pass filter into the amplifier. A typical
application for this is to block out the band noise caused by the output of a DAC. When selecting
capacitance values, the cut-off frequency of the filter becomes 1/(
π
× R × C) instead of 1/(2
π
× R × C)
because the capacitor is connected differentially, which halves the required capacitance.
3.4
Special Note on Gain and Input Configurations
The TPA6120A2RGY high-fidelity audio power amplifier has two separate channels, left and right. It is not
necessary to operate each channel in the same configuration. For test purposes, it may be desirable to
operate the left channel with a noninverting configuration, and the right channel with an inverting
configuration. One channel may be configured to operate with differential inputs while the other channel
with single-ended inputs. The TPA6120A2RGY EVM allows for this flexibility. From a listening standpoint,
the best audio performance is achieved when both channels are operated with the same configuration. In
this case, there is no sound difference between the left and right channels for the human ear to detect.
3.5
Single Power Supply Configuration
The TPA6120A2RGY EVM was not optimized for single power supply operation. To operate in this mode,
the V– terminal must be connected to GND. DC-blocking capacitors must be used at the outputs to
prevent large amounts of dc current from flowing through the headphones due to the high midrail bias.
Likewise, dc-blocking capacitors must be used at the input. R9 and R10 must be removed. The positive
input nodes must be biased to midrail. Resistors R9 and R10 tie the positive node to ground.
4
TPA6120A2RGY Evaluation Module
SLOU394 – July 2014
Copyright © 2014, Texas Instruments Incorporated
