www.ti.com

CAPACITOR SELECTION

TPA2013D1

SLOS520 – AUGUST 2007

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 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 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

Copyright © 2007, Texas Instruments Incorporated

Submit Documentation Feedback

15

Product Folder Link(s): TPA2013D1