The TPA0242 Audio Power Amplifier Evaluation Module
3.2.4Depop Circuitry
The TPA0242 amplifier IC contains internal circuitry to minimize the various transients that might appear at the output during the transition from power off or shutdown to normal operation, or when transitioning between the SE and BTL modes.
3.2.5BTL Operation
To operate in the bridge-tied load output mode, the module SE/BTL control input terminal must be held low. The module output signal from OUT+ must go through the speaker load and be returned directly to OUT±, and NOT to system ground. This requires that the OUT± line be isolated not only from system ground, but also from the OUT± lines of any other amplifiers in the system. The platform provides such isolated output lines from the amplifier EVM sockets directly to separate left and right speaker connectors.
3.2.6Single-Ended Operation
For single-ended operation, the module SE/BTL control input pin must be held high. The speaker (or headphone) load is connected to the module OUT+ output pin through a coupling capacitor, and to platform/system ground. A 470 -∝F electrolytic coupling capacitor is provided on the platform in the signal path to the headphone output jack for this purpose, and a control signal from the platform headphone jack can be routed to the module control input pin to switch the TPA0242 IC to the single-ended mode.
In the single-ended mode, the amplifiers inside the TPA0242 IC that drive the OUT± lines do not operate and do not dissipate any power. The OUT± pins go into a high-impedance state and can be left connected or allowed to float.
