Texas Instruments TPA0232, User Manual, Page: 24 / 36

The TPA0232 Audio Power Amplifier Evaluation Module
3-6 Details
Potentiometer R2 adjusts the gain of the internal preamp stage of the TPA0232
amplifier by adjusting the control voltage applied to the VOLUME terminal
(pin 3) of the IC. Rotating the potentiometer slider clockwise decreases the
applied control voltage, resulting in a higher volume. Table 3–1 shows the
relationship between the control voltage applied to the VOLUME terminal and
the effective amplifier gain. Headphone gain is reduced by 6 dB.
Table 3–1. TPA0232 EVM BTL Volume Settings
VOLUME (Pin 3) BTL VOLUME (Pin 3) BTL VOLUME (Pin 3) BTL
FROM
(V)
TO
(V)
GAIN
(dB)
FROM
(V)
TO
(V)
GAIN
(dB)
FROM
(V)
TO
(V)
GAIN
(dB)
0 0.15 20 1.28 1.39 –2 2.52 2.63 –24
0.15 0.28 18 1.39 1.5 –4 2.63 2.74 –26
0.28 0.39 16 1.5 1.62 –6 2.74 2.86 –28
0.39 0.5 14 1.62 1.73 –8 2.86 2.97 –30
0.5 0.61 12 1.73 1.84 –10 2.97 3.08 –32
0.61 0.73 10 1.84 1.95 –12 3.08 3.2 –34
0.73 0.84 8 1.95 2.07 –14 3.2 3.31 –36
0.84 0.95 6 2.07 2.18 –16 3.31 3.42 –38
0.95 1.06 4 2.18 2.29 –18 3.42 3.54 –40
1.06 1.17 2 2.29 2.41 –20 3.54 5 –85
1.17 1.28 0 2.41 2.52 –22
Since the overall gain of the amplifier is set by the internal preamp stage and
not by the power amplifier stage, the TPA0232 maintains the same total
harmonic distortion (THD) at even the highest gain settings.
3.2.3 Differential Input
The TPA0232 line inputs allow the use of a single-ended or differential audio
source. The differential input stage of the amplifier cancels any noise that
appears on both input lines of a channel. To use the TPA0232 EVM with a
differential source, connect the positive lead of the audio source to the R LINE–
(L LINE–) input and the negative lead from the audio source to the R IN+
(L IN+) input. To use the TPA0232 with a single-ended source, ac-ground the
R IN+ and L IN+ inputs and apply the audio signal to the R LINE– and L LINE–
inputs. Line and headphone inputs share common positive inputs. If using
separate line and headphone inputs, R IN+ and L IN+ should be ac-grounded.
If using differential inputs, line and headphone inputs must be the same. In a
single-ended input application, the R IN+ and L IN+ inputs should be
ac-grounded at the audio source instead of at the device inputs for best noise
performance.