Texas Instruments TPA0103 manual Mode Control, Headphone Jack Control Signals

Using The TPA0103 EVM With the Plug-N-Play Evaluation Platform

3.3.4Mode Control

The TPA0103 EVM is equipped with a mode control input pin that receives a control signal from the platform. This EVM pin is connected to the amplifier IC Mode A output mode control input pin. The state of this input, in conjunction with the state of the Mode B output mode control input pin, controls the output mode of the amplifier IC on the EVM.

When the EVM mode control input pin (Mode A) is high, the TPA0103 amplifier IC on the module either enters the mute mode and dissipates very little power when Mode B jumper S2 on the EVM is set to OFF. When S2 is set to ON, a high on the EVM mode control input pin causes the amplifier IC to enter the L/R stereo outputs only mode.

When the EVM mode control input is tied to GND or allowed to float, the 3-channel output mode is selected if S2 is set to OFF and the center channel only output mode is selected if S2 is set to ON.

In the typical application, output mode switching allows the TPA0103 to operate the BTL center channel to drive a speaker and then switch to stereo left and right 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 (Figure 3±7). 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±7. 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

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