AAT3216 ETC, AAT3216 Datasheet - Page 9

• Manufacturer Part Number: AAT3216
• Description: 150mA MicroPower LDO with PowerOK
• Manufacturer: ETC

Applications Information
To assure the maximum possible performance is
obtained from the AAT3216, please refer to the fol-
lowing application recommendations.
Input Capacitor
Typically a 1µF or larger capacitor is recommend-
ed for C
not required for basic LDO regulator operation.
However, if the AAT3216 is physically located more
than 3 centimeters from an input power source, a
C
C
as practically possible. C
1µF will offer superior input line transient response
and will assist in maximizing the highest possible
power supply ripple rejection.
Ceramic, tantalum or aluminum electrolytic capaci-
tors may be selected for C
capacitor ESR requirement for C
150mA LDO regulator output operation, ceramic
capacitors are recommended for C
inherent capability over tantalum capacitors to with-
stand input current surges from low impedance
sources such as batteries in portable devices.
Output Capacitor
For proper load voltage regulation and operational
stability, a capacitor is required between pins V
and GND.
the LDO regulator ground pin should be made as
direct as practically possible for maximum device
performance.
The AAT3216 has been specifically designed to func-
tion with very low ESR ceramic capacitors. For best
performance, ceramic capacitors are recommended.
Typical output capacitor values for maximum output
current conditions range from 1µF to 10µF.
Applications utilizing the exceptionally low output
noise and optimum power supply ripple rejection
characteristics of the AAT3216 should use 2.2µF or
greater for C
without limit.
In low output current applications where output
load is less then 10mA, the minimum value for
C
3216.2004.01.0.94
IN
IN
OUT
should be located as close to the device V
capacitor will be needed for stable operation.
can be as low as 0.47µF.
IN
in most applications. A C
OUT
The C
. If desired, C
OUT
capacitor connection to
IN
IN
. There is no specific
OUT
values greater than
may be increased
IN
. However, for
IN
IN
due to their
capacitor is
IN
150mA MicroPower™ LDO with PowerOK
OUT
pin
Capacitor Characteristics
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use
with the AAT3216. Ceramic capacitors offer many
advantages over their tantalum and aluminum elec-
trolytic counterparts. A ceramic capacitor typically
has very low ESR, is lower cost, has a smaller PCB
footprint and is non-polarized. Line and load tran-
sient response of the LDO regulator is improved by
using low ESR ceramic capacitors. Since ceramic
capacitors are non-polarized, they are not prone to
incorrect connection damage.
Equivalent Series Resistance (ESR): ESR is a
very important characteristic to consider when
selecting a capacitor. ESR is the internal series
resistance associated with a capacitor, which
includes lead resistance, internal connections, size
and area, material composition and ambient tem-
perature. Typically capacitor ESR is measured in
milliohms for ceramic capacitors and can range to
more than several ohms for tantalum or aluminum
electrolytic capacitors.
Ceramic Capacitor Materials: Ceramic capaci-
tors less than 0.1µF are typically made from NPO
or COG materials. NPO and COG materials are
typically tight tolerance very stable over tempera-
ture. Larger capacitor values are typically com-
posed of X7R, X5R, Z5U and Y5V dielectric mate-
rials. Large ceramic capacitors, typically greater
then 2.2µF are often available in the low cost Y5V
and Z5U dielectrics. These two material types are
not recommended for use with LDO regulators
since the capacitor tolerance can vary more than
±50% over the operating temperature range of the
device. A 2.2µF Y5V capacitor could be reduced to
1µF over temperature, this could cause problems
for circuit operation. X7R and X5R dielectrics are
much more desirable. The temperature tolerance
of X7R dielectric is better than ±15%.
Capacitor area is another contributor to ESR.
Capacitors which are physically large in size will have
a lower ESR when compared to a smaller sized
capacitor of an equivalent material and capacitance
value. These larger devices can improve circuit tran-
sient response when compared to an equal value
capacitor in a smaller package size.
AAT3216
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