The TPA301 Audio Power Amplifier Evaluation Module
3.2.1TPA301 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
| 4 | _ | |
| | 5 |
| IN – | |
| 3 | + | OUT+ |
| IN+ | |
| | |
| 6 | | |
| VDD | | |
| 2 | VDD/2 | |
| | _ | 8 |
| 7 | |
| + | OUT– |
| |
| GND | |
| | |
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.
3.2.2BTL 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.
3.2.3SIngle-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 -∝F electrolytic coupling capacitor is provided on the platform in the signal path to the headphone output jack.
