TPA302

300-mW STEREO AUDIO POWER AMPLIFIER

SLOS174B – JANUARY 1997 – REVISE MARCH 2000

18

POST OFFICE BOX 655303

APPLICATION INFORMATION

Table 1. Common Load Impedances vs Low Frequency Output Characteristics in SE Mode

RL

CC

LOWEST FREQUENCY

8

Ω

68

µF

293 Hz

32

Ω

68

µF

73 Hz

47,000

Ω

68

µF

0.05 Hz

As Table 1 indicates, most of the bass response is attenuated into 8-

Ω loads while headphone response is

adequate and drive into line level inputs (a home stereo for example) is very good.

The output coupling capacitor required in single-supply SE mode also places additional constraints on the

selection of other components in the amplifier circuit. The rules described earlier still hold with the addition of

the following relationship:

(8)

1

C

B

25 k

Ω

v

1

C

1

R

shutdown mode

the absolute minimum level during periods of nonuse for battery-power conservation. For example, during

device sleep modes or when other audio-drive currents are used (i.e., headphone mode), the speaker drive is

not required. The SHUTDOWN input terminal should be held low during normal operation when the amplifier

is in use. Pulling SHUTDOWN high causes the outputs to mute and the amplifier to enter a low-current state,

using low-ESR capacitors

Low-ESR capacitors are recommended throughout this applications section. A real capacitor can be modeled

simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the

beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance the more the

real capacitor behaves like an ideal capacitor.