The TPA152 Audio Power Amplifier Evaluation Module
3-5
Details
3.2.2
Module Gain
The TPA152 evaluation module has a set gain of 1 (inverting) for each channel.
However, the gain can be adjusted to a maximum of approximately 10
(inverting) by changing the value of feedback resistors (R2 and R4, Figure
3–3). Use the following equation to determine the value of R
F:
Gain
+
– R
F
R
I
The TPA152 amplifier IC, as most other amplifiers, exhibits its best distortion
and noise performance at lower gain levels. In addition, higher gain levels
require a small compensation capacitor to ensure stability (see the TPA152
data sheet).
Gain versus total harmonic distortion (THD) and gain versus signal-to-noise
ratio (SNR) should be considered in each application. Both the module input
signal level and the TPA152 module gain should be adjusted to obtain the
lowest overall distortion level for a particular overall gain. A quick rule of thumb
(everything else being equal): the module input signal level should be as high
as possible without clipping or overloading the TPA152 input, and the TPA152
gain should be kept as low as possible.
3.2.3
Mute
When the mute terminal of the TPA152 amplifier IC is taken high, the IC ceases
operation. This is accomplished by applying a control signal to the module SD
pin or by pressing the Shutdown switch, S1, on the module. When the control
signal goes low or is removed (or the switch is released), amplifier operation
resumes.
The Plug-N-Play platform can generate the mute signal for the module either
when a plug is
inserted into the platform headphone output jack or when the
plug is
removed, as selected by a platform jumper (JP7).
