Datasheet

TPA0202

2-W STEREO AUDIO POWER AMPLIFIER

SLOS205B – FEBRUARY 1998 – REVISED DECEMBER 2000

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

APPLICATION INFORMATION

input capacitor, C

In the typical application an input capacitor, C

, is required to allow the amplifier to bias the input signal to the

proper dc level for optimum operation. In this case, C

and R

form a high-pass filter with the corner frequency

determined in equation 8.

(8)

–3 dB

c(highpass)

2 R

The value of C

is important to consider as it directly affects the bass (low frequency) performance of the circuit.

Consider the example where R

is 10 kΩ and the specification calls for a flat bass response down to 40 Hz.

Equation 8 is reconfigured as equation 9.

(9)

2 R

In this example, C

is 0.40 µF so one would likely choose a value in the range of 0.47 µF to 1 µF. A further

consideration for this capacitor is the leakage path from the input source through the input network (R

, C

) and

the feedback resistor (R

) to the load. This leakage current creates a dc offset voltage at the input to the amplifier

that reduces useful headroom, especially in high gain applications. For this reason a low-leakage tantalum or

ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor

should face the amplifier input in most applications as the dc level there is held at V

/2, which is likely higher

that the source dc level. Please note that it is important to confirm the capacitor polarity in the application.

power supply decoupling, C

The TPA0202 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling

to ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also

prevents oscillations for long lead lengths between the amplifier and the speaker. The optimum decoupling is

achieved by using two capacitors of different types that target different types of noise on the power supply leads.

For higher frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance

(ESR) ceramic capacitor, typically 0.1 µF placed as close as possible to the device V

lead works best. For

filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near

the audio power amplifier is recommended.