TPA032D04

10W STEREO CLASSD AUDIO POWER AMPLIFIER

SLOS203B − DECEMBER 1999 − REVISED JUNE 2000

12

TI.COM

POST OFFICE BOX 1443

APPLICATION INFORMATION

high-pass filter with the corner frequency determined in equation 8.

(8)

f

c(highpass) +

1

2

pZ

I

C

I

−3 dB

fc

Consider the example where the specification calls for a flat bass response down to 40 Hz. Equation 8 is

reconfigured as equation 9.

(9)

C

1

2

pZ

I

fc

tantalum or ceramic capacitor is the best choice for the input capacitors. When polarized capacitors are used,

the positive side of the capacitor should face the amplifier input, as the dc level there is held at 1.5 V, which is

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

application.

differential input

The TPA032D04 has differential inputs to minimize distortion at the input to the IC. Since these inputs nominally

sit at 1.5 V, dc-blocking capacitors are required on each of the four input terminals. If the signal source is

single-ended, optimal performance is achieved by treating the signal ground as a signal. In other words,

reference the signal ground at the signal source, and run a trace to the dc-blocking capacitor, which should be

located physically close to the TPA032D04. If this is not feasible, it is still necessary to locally ground the unused

input terminal through a dc-blocking capacitor.

The TPA032D04 is a high-performance Class-D 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

leads, 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.

The TPA032D04 has several different power supply terminals. This was done to isolate the noise resulting from

high-current switching from the sensitive analog circuitry inside the IC.