AAT3141_07 Datasheet, PDF (15/16 Pages) Advanced Analogic Technologies – High Efficiency 1X/1.5X/2X Charge Pump for White LED Applications

AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
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 have tight tolerance and are stable over
temperature. Large capacitor values are composed
of X7R, X5R, Z5U, or Y5V dielectric materials.
Large ceramic capacitors, typically greater than
2.2µF, are often available in low-cost Y5V and Z5U
dielectrics, but capacitors greater than 1µF are usu-
ally not required for AAT3141 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.
Thermal Protection
The AAT3141 has a thermal protection circuit that
will shut down the charge pump if the die tempera-
ture rises above the thermal limit, as is the case
during a short-circuit of the CP pin.
Charge Pump Compatibility
The four-output AAT3141 is pin-compatible with the
AAT3123, AAT3132, and AAT3113 in TSOPJW-12
packages. The AAT3141 offers an improved overall
efficiency, wider operating range, and the ability to
drive high-V_F type LEDs at full current. The
AAT3141 is well suited for battery-powered appli-
cations using single-cell lithium-ion/polymer batter-
ies and 3-series connected dry cells (3.6V).
3141.2007.03.1.3
15