Using The TPA701 MSOP EVM With the
3.3.2Signal Routing
Signal flow on the platform is controlled by two signal routing switches, as shown in Figure 3±5.
Figure 3±5. Platform Signal Routing and Outputs
R |
| |
Audio | U1 | |
Signal | ||
Input | ||
Conditioning | ||
| ||
L |
|
Off
S2
On
U3 |
|
| + |
|
TPA701 | R |
| R |
|
Amplifier EVM |
| ± | J7, J8, J9 | |
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| |
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| Speaker |
U4 |
|
| ± | Outputs |
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| ||
TPA701 | L |
| L |
|
Amplifier EVM |
| + |
| |
| U2 ± U4 |
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|
| R |
|
U5 | R |
| + |
|
Stereo |
| GND | ± | J10 |
Headphone | S3 |
| Headphone | |
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| |||
Amplifier | L |
| ± | Output |
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|
| + |
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| L |
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| U5 |
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3.3.2.1Signal 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 TPA701 power amplifiers.
-Switch S2 selects signal conditioning or bypasses it
3.3.3Mute/Mode
The TPA701 MSOP EVM is equipped with a shutdown (mute) control input pin. When this input is tied to VDD, the TPA701 amplifier IC on the module shuts down and assumes an
In typical applications, as often found in notebook computers, portable audio products, and such, the internal speakers mute when headphones are plugged into the headphone jack, or internal speakers mute when external speakers are connected. In applications using separate speaker and headphone amplifiers, the one not being used can be shut down (muted) to conserve power.
3.3.3.1Headphone 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±6). Each control line is pulled down by a
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