TPA2014D1 Datasheet, PDF (14/27 Pages) Texas Instruments – 1.5-W CONSTANT OUTPUT POWER CLASS-D AUDIO AMPLIFIER WITH INTEGRATED BOOST CONVERTER

TPA2014D1
SLAS559A – MAY 2008 – REVISED JUNE 2008 ............................................................................................................................................................... www.ti.com
CAPACITOR SELECTION
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.
High-K material is very sensitive to applied dc voltage. X5R capacitors can have losses ranging from 15 to 45%
of their initial capacitance with only half of their dc rated voltage applied. For example, if 5 Vdc is applied to a 10
V, 1 µF X5R capacitor, the measured capacitance at that point may show 0.85 µF, 0.55 µF, or somewhere in
between. Y5V capacitors have losses that can reach or exceed 50% to 75% of their rated value.
In an application, the working capacitance of components made with high-K materials is generally 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 results 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 TPA2014D1.
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 TPA2014D1. The
TPA2014D1 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/–20%
Temperature Coefficient
±30ppm
±15%
22/–82%
Temperature Range, °C
–55/125°C
–55/125°C
-30/85°C
14
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