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The TPA301 Audio Power Amplifier Evaluation Module
3-4
Details
3.2.1 TPA301 Audio Amplifier IC
The TPA301 audio amplifier IC is a CMOS device intended primarily for bridge-
tied load (BTL) operation in battery-powered applications. It is supplied in a
very small surface-mount package and has been designed to operate from low
supply voltages (between approximately 2.5 V and 5.5 V) and deliver up to
approximately 350 mW into an 8-Ω, BTL (Figure 3–4). Typical applications in-
clude portable phones, toys, games, and similar hand-held audio applications.
Figure 3–4. TPA301 Amplifier IC
5
OUT+
4
IN –
OUT–
8
3
IN+
_
_
+
+
7
2
V
DD
/2
V
DD
GND
6
The amplifier IC includes two separate amplifiers that operate 180°
out-of-phase with each other for increased power (BTL). The speaker load is
connected directly across OUT+ and OUT–, and neither line is connected to
ground. Although the amplifier can operate in the single-ended mode, there
are many benefits to the BTL output configuration including no bulky output
coupling capacitors and quadruple the output power. For more information,
see the TPA301 amplifier IC data sheet, TI Literature Number SLOS208.
3.2.2 BTL Operation
To operate in the bridge-tied load output configuration, 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 EVM sockets directly to separate left and right speaker connectors.
3.2.3 SIngle-Ended Operation
For single-ended operation, the speaker (or headphone) load is connected to
the module OUT+ output pin through a coupling capacitor, and to
platform/system ground. The module OUT– pin can be connected to the
module DL pin, a dummy-load circuit on the module, for improved amplifier
stability (however, this is not required). A 470-µF electrolytic coupling
capacitor is provided on the platform in the signal path to the headphone output
jack.