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TPA2012D2

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SLOS438F – DECEMBER 2004 – REVISED MARCH 2017

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Copyright © 2004–2017, Texas Instruments Incorporated

Typical Applications (continued)

10.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 2.

Table 2. Design Parameters

PARAMETER

VALUE

Power supply

5 V

Enable inputs

High > 1.3 V

Low < 0.35 V

Speaker

8 Ω

10.2.1.2 Detailed Design Procedure

10.2.1.2.1

Surface Mount Capacitors

Temperature and applied DC voltage influence the actual capacitance of high-K materials. Table 3 shows the

relationship between the different types of high-K materials and their associated tolerances, temperature

coefficients, and temperature ranges. Notice that a capacitor made with X5R material can lose up to 15% of its

capacitance within its working temperature range.

In an application, the working capacitance of components made with high-K materials is generally much lower

than nominal capacitance. A worst-case result with a typical X5R material might be –10% tolerance, –15%

temperature effect, and –45% DC voltage effect at 50% of the rated voltage. This particular case would result in

a working capacitance of 42% (0.9 × 0.85 × 0.55) of the nominal value.

Select high-K ceramic capacitors according to the following rules:

1. Use capacitors made of materials with temperature coefficients of X5R, X7R, or better.

2. Use capacitors with DC voltage ratings of at least twice the application voltage. Use minimum 10-V

capacitors for the TPA2012D2.

3. Choose a capacitance value at least twice the nominal value calculated for the application. Multiply the

nominal value by a factor of 2 for safety. If a 10-µF capacitor is required, use 20 µF.

The preceding rules and recommendations apply to capacitors used in connection with the TPA2012D2. The

TPA2012D2 cannot meet its performance specifications if the rules and recommendations are not followed.

Table 3. Typical Tolerance and Temperature Coefficient of Capacitance by Material

MATERIAL

COG/NPO

X7R

X5R

Typical tolerance

±5%

±10%

80% to –20%

Temperature

±30 ppm

±15%

22% to –82%

Temperature range (°C)

–55°C to 125°C

–55°C to 125°C

–30°C to 85°C

10.2.1.2.2

The TPA2012D2 is a high-performance Class-D audio amplifier that requires adequate power supply decoupling

to ensure the efficiency is high and total harmonic distortion (THD) is low. For higher frequency transients,

spikes, or digital hash on the line a good low equivalent-series-resistance (ESR) ceramic capacitor, typically

the TPA2012D2 is important for the efficiency of the Class-D amplifier, because any resistance or inductance in

the trace between the device and the capacitor can cause a loss in efficiency. For filtering lower-frequency noise

signals, a 4.7 µF or greater capacitor placed near the audio power amplifier would also help, but it is not required

in most applications because of the high PSRR of this device.

10.2.1.2.3

The TPA2012D2 does not require input coupling capacitors if the design uses a differential source that is biased

high-pass filtering is needed (see Figure 37), or if using a single-ended source (see Figure 38), input coupling

capacitors are required.