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3 signal routing, Figure 3–6. platform signal routing and outputs – Texas Instruments TPA0202 User Manual

Page 27

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Using The TPA0202 EVM With the Plug-N-Play Evaluation Platform

3-11

Details

3.3.3

Signal Routing

Signal flow on the platform is controlled by two signal routing switches, as
shown in Figure 3 – 5.

Figure 3–6. Platform Signal Routing and Outputs

U1

Signal

Conditioning

On

Off

U5

Stereo

Headphone

Amplifier

S2

R

L

R

L

L

U5

U2 – U4

S3

J10

Headphone

Output

R

L

Audio

Input

R

L

J7, J8, J9

Speaker
Outputs

R

+

+

U2

TPA0202

Amplifier EVM

+

+

GND

3.3.3.1

Signal Conditioning

The audio signal from the input jacks can be applied to the signal conditioning
socket (U1) if an EVM is installed there, or socket U1 can be bypassed and the
audio input signal applied directly to the inputs of the TPA0202.

-

Switch S2 selects signal conditioning or bypasses it

3.3.3.2

Headphone Output Jack

Switch S3 is the source select for the stereo headphone output jack, J10. The
headphone jack is capacitively coupled (via 470

µ

F electrolytics) and can

output either the signal from the headphone amplifier in socket U5, or the
signal from the TPA0202 power amplifier installed in socket U2, as determined
by the setting of headphone source select switch S3.

When S3 is set to the power amplifier position (U2 – U4), the headphone jack
is connected to the TPA0202 power amplifier OUT+ output lines. When a plug
is inserted into the jack, signals output through J10 are returned to platform
ground, requiring single-ended power amplifier operation. A switch inside the
headphone jack produces a control signal that can be routed to the power
amplifier socket to shut down the TPA0202 EVM or switch it to single-ended
output mode when a plug is inserted.

Source select switch S3 connects the headphone jack to the output lines of
either the headphone amplifier socket U5, or the power amplifier sockets
(U2 – U4).

J

To keep the TPA0202 amplifier outputs separated, set switch S3 to the
headphone amplifier position (

U5 ) and use the speaker outputs (J7,

J8, and J9)

J

To route the TPA0202 amplifier outputs to the headphone output jack
(J10), set switch S3 to the power amplifier position (

U2 – U4 ) — use

this setting

only if the TPA0202 EVM is to drive single-ended loads

connected to J10