Texas Instruments TPA0103 User Manual download pdf (Page 26)

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

3-12

Details

3.3.4 Mode 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.

3.3.4.1 Headphone 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-kΩ resistor to ground (R4 and R5). The

switch in the headphone jack pulls one line or the other up to V

through a

240-Ω resistor (R3), depending on whether a plug is inserted in J10 or not.

Figure 3–7. Mute/Mode and Polarity Control

J10

Headphone

Jack

240 Ω

1 kΩ

JP8 JP6

Power

Amplifier

Polarity

Mode

Mute

SPK

(U2–U4)

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Texas Instruments TPA0103 User Manual Page 26