Texas Instruments SLOU121 8.Mute/Mode and Polarity Control, 3.3.4.1Headphone Jack Control Signals

Using the TPA6011A4 EVM With the Plug-N-Play Evaluation Platform

output mode. When the mode control input is tied to GND, the module operates in the BTL output mode. When this input is tied to VDD, the module operates in the single-ended output mode.

In the typical application, output mode switching allows the TPA6011A4 to operate in the BTL output mode for increased power to internal speakers and then switch to single-ended mode to drive headphones when a plug is inserted into the headphone jack.

3.3.4.1Headphone Jack Control Signals

The platform headphone output jack (J10) contains an internal switch that changes the state of a pair of control lines when a plug is inserted (see Figure 3–8). Each control line is pulled down by a 1-kΩresistor to ground (R4 and R5). The switch in the headphone jack pulls one line or the other up to VDD through a 240-Ωresistor (R3) depending on whether a plug is inserted in J10 or not.

Figure 3–8. Mute/Mode and Polarity Control

	VDD
	R3	Polarity
	240 Ω
		JP8
J10		Lo

Headphone

Jack		Hi
R4	R5
		SPK
1 kΩ	1 kΩ	(U2–U4)

JP6

Mode	U2
	Power
Mute	Amplifier

3.3.4.2Mute/Mode Select (JP6)

A 3-pin jumper header (JP6) on the platform, functioning as an SPDT switch, routes the control signal from the headphone jack to either the shutdown control input pin or the mode control input pin of the evaluation module.

-To shut down the TPA6011A4 amplifier module using the control signal from the platform headphone jack, jumper JP6 to MUTE.

-To switch the output mode of the TPA6011A4 amplifier between BTL and single-ended using the control signal from the platform headphone jack, jumper JP6 to MODE.

3.3.4.3Mute/Mode Polarity Select (JP8)

A second 3-pin jumper header (JP8) on the platform selects the control signal polarity by connecting either the active-high or the active-low line from the headphone jack to jumper JP6.

-When JP6 is set to mute, use the following JP8 settings for the TPA6011A4:

J To shut down the TPA6011A4 amplifier module when a plug is inserted into the headphone jack, jumper JP8 to Lo (this is the typical setting).

J To shut down the TPA6011A4 amplifier module until a plug is inserted into the headphone jack, jumper JP8 to Hi.

3-14 Details