Texas Instruments SLOU121 3.2.2Inputs and Gain, 3.2.3Volume Control, 4.TPA6011A4 Amplifier IC

The TPA6011A4 Audio Power Amplifier Evaluation Module

In the single-ended mode, the headphone inputs are automatically selected and the speaker load is connected between the OUT+ terminal, through an output coupling capacitor, to system ground. For more information, see the TPA6011A4 amplifier IC data sheet, TI literature number SLOS392.

Figure 3–4. TPA6011A4 Amplifier IC

L HP

L IN+

L LINE–

FADE

RLINE– R IN+

R HP

MUX
VOLUME	SEDIFF
	VOLUME
CONTROL
	SEMAX
MUX
HP/LINE	SE/BTL

3.2.2Inputs and Gain

Each channel has two separate signal inputs, line and headphone (HP ), that are automatically selected with the output mode (SE/BTL). An input multiplexor in the amplifier IC selects the HP inputs when the IC is in the SE output mode and the line inputs when in the BTL output mode.

Line and headphone inputs share common positive inputs. If using separate line and headphone inputs, R IN+ and L IN+ should be ac-grounded through a capacitor. If using differential inputs, line and headphone inputs must be the same.

3.2.3Volume Control

Potentiometer R5 adjusts the gain of the amplifier when the amplifier is in BTL mode (a logic low on the SE/BTL pin). Turning the potentiometer clockwise increases the voltage on the VOLUME terminal (pin 21), resulting in a higher volume. Turning the potentiometer counter-clockwise decreases the voltage on the VOLUME terminal (pin 21), resulting in a lower volume. Table 3–1 lists the corresponding gain for the voltage applied to the VOLUME terminal. The voltages listed in the table are for VDD = 5 V. For a different VDD, the values in the table scale linearly. If VDD = 4 V, multiply all the voltages in the table by 4 V/5 V, or 0.8.

The TPA6011A4 allows the user to specify a difference between BTL gain and SE gain. When switching to SE mode (a logic high on the SE/BTL pin), the

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