TPA4861

1-W AUDIO POWER AMPLIFIER

SLOS163B – SEPTEMBER 1996 – REVISED MARCH 2000

21

POST OFFICE BOX 655303

APPLICATION INFORMATION

at the output of the amplifier thus preventing dc currents in the load. As with the input coupling capacitor, the

output coupling capacitor and impedance of the load form a high-pass filter governed by equation 13.

(13)

f

1

2

pR

The main disadvantage, from a performance standpoint, is that the load impedances are typically small, which

summarizes the frequency response characteristics of each configuration.

Table 2. 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 2 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.

shutdown mode

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,

unpredictable.

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.