TPA2013D1_16 Datasheet, PDF (20/40 Pages) Texas Instruments – Constant Output Power Class-D Audio Amplifier

TPA2013D1
SLOS520A – AUGUST 2007 – REVISED MARCH 2016
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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 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 TPA2013D1.
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 TPA2013D1. The
TPA2013D1 cannot meet its performance specifications if the rules and recommendations are not followed.
Table 6. Typical Tolerance and Temperature Coefficient of Capacitance by Material
MATERIAL
Typical Tolerance
Temperature Coefficient
Temperature Range, °C
COG/NPO
±5%
±30ppm
–55/125°C
X7R
±10%
±15%
–55/125°C
X5R
80/–20%
22/–82%
–30/85°C
10.2.1.2.3.2 TPA2013D1 Capacitor Equations
The value of the boost capacitor is determined by the minimum value of working capacitance required for stability
and the maximum voltage ripple allowed on V_CC in the application. The minimum value of working capacitance is
10 μF. Do not use any component with a working capacitance less than 10 μF.
For X5R or X7R ceramic capacitors, Equation 4 shows the relationship between the boost capacitance, C, to
load current, load voltage, ripple voltage, input voltage, and switching frequency (I_CC, V_CC, ΔV, V_DD, f_boost
respectively). Insert the maximum allowed ripple voltage into Equation 4 to solve for C. A factor of 2 is included
to implement the rules and specifications listed earlier.
C = 2 ´ ^{ICC ´ (VCC - VDD )}
DV ´ f_boost ´ V_CC
(4)
For aluminum or tantalum capacitors, Equation 5 shows the relationship between the boost capacitance, C, to
load current, load voltage, ripple voltage, input voltage, and switching frequency (I_CC, V_CC, ΔV, V_DD, f_boost
respectively). Insert the maximum allowed ripple voltage into Equation 5 to solve for C. Solve this equation
assuming ESR is zero.
C = ^{ICC ´ (VCC - VDD )}
DV ´ f_boost ´ V_CC
(5)
Capacitance of aluminum and tantalum capacitors is normally not sensitive to applied voltage, so there is no
factor of 2 included in Equation 5. However, the ESR in aluminum and tantalum capacitors can be significant.
Choose an aluminum or tantalum capacitor with ESR around 30 mΩ. For best perfornamce using of tantalum
capacitor, use at least a 10-V rating.
NOTE
Tantalum capacitors must generally be used at voltages of half their ratings or less.
10.2.1.2.4 Recommended Inductor and Capacitor Values by Application
Use Table 7 as a guide for determining the proper inductor and capacitor values.
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