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3.2.3
Differential Input
The TPA0152 line inputs allow the use of a single-ended or differential audio
source. The differential input stage of the amplifier cancels any noise that
appears on both input lines of a channel. To use the TPA0152 EVM with a
differential source, connect the positive lead of the audio source to the R LINE–
(L LINE–) input and the negative lead from the audio source to the R IN+
(L IN+) input. To use the TPA0152 with a single-ended source, AC-ground the
R IN+ and L IN+ inputs and apply the audio signal to the R LINE– and L LINE–
inputs. Line and headphone inputs share common positive inputs. If using
separate line and headphone inputs, R IN+ and L IN+ should be AC-grounded.
If using differential inputs, line and headphone inputs must be the same. In a
single-ended input application, the R IN+ and L IN+ inputs should be AC
grounded at the audio source instead of at the device inputs for best noise
performance.
3.2.4
Depop Circuitry
The TPA0152 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.
3.2.5
BTL 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.
3.2.6
Single-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 -µF 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 TPA0152 IC to the single-ended mode.
In the single-ended mode, the amplifiers inside the TPA0152 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.
The TPA0152 Audio Power Amplifier Evaluation Module
Details
3-7
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