AAT3153 datasheet(12/14 Pages) AAT

12 / 14 page

trolytic counterparts. A ceramic capacitor has very

low ESR, is lowest cost, has a smaller PCB foot-

print, and is non-polarized. Low ESR ceramic

capacitors help to maximize charge pump transient

response. Since ceramic capacitors are non-polar-

ized, they are not prone to incorrect connection

damage.

Equivalent Series Resistance

ESR is an important characteristic to consider

when selecting a capacitor. ESR is a resistance

internal to a capacitor that is caused by the leads,

internal connections, size or area, material compo-

sition, and ambient temperature. Capacitor ESR is

typically measured in milliohms for ceramic capac-

itors and can range to more than several ohms for

tantalum or aluminum electrolytic capacitors.

Ceramic Capacitor Materials

Ceramic capacitors less than 0.1µF are typically

made from NPO or C0G materials. NPO and C0G

materials generally have tight tolerance and are

very stable over temperature. Larger capacitor val-

ues are usually composed of X7R, X5R, Z5U, or

Y5V dielectric materials. Large ceramic capacitors

(i.e., greater than 2.2µF) are often available in low-

cost Y5V and Z5U dielectrics, but capacitors

greater than 1µF are not typically required for

AAT3153 applications.

Capacitor area is another contributor to ESR.

Capacitors that are physically large will have a lower

ESR when compared to an equivalent material

smaller capacitor. These larger devices can improve

circuit transient response when compared to an

equal value capacitor in a smaller package size.

AAT3153

High Efficiency 1X/1.5X/2X Charge Pump

For White LED Applications

3153.2005.12.0.93

AAT3153 Datasheet(PDF) 12 Page - Advanced Analog Technology, Inc.