Advanced Power
Electronics Corp.
Application Information
The
APE8800A
is a low dropout linear regulator that
could provide 300mA output current at dropout volt-
age about 250mV. Current limit and on chip thermal
shutdown features provide protection against any
combination of overload or ambient temperature that
could exceed maximum junction temperature.
1. Output and Input Capacitor
The
APE8800A
regulator is designed to be stable
with a wide range of output capacitors. The ESR
of the output capacitor affects stability. Larger
value of the output capacitor decreases the peak
deviations and improves transient response for
larger current changes.
The capacitor types (aluminum, ceramic, and tant-
alum) have different characterizations such as
temperature and voltage coefficients. All ceramic
capacitors are manufactured with a variety of
dielectrics, each with different behavior across
temperature and applications. Common dielectrics
used are X5R, X7R and Y5V. It is recommended
to use 1uF to 10uF X5R or X7R dielectric ceramic
capacitors with 30mΩ to 50mΩ ESR range betw-
een device outputs and ground for stability. The
APE8800A
is designed to be stable with low ESR
ceramic capacitors and higher values of cap-
acitors and ESR could improve output stability.
The ESR of output capacitor is very important
because it generates a zero to provide phase lead
for loop stability.
APE8800A
There are no requirements for the ESR on the
input capacitor, but its voltage and temperature
coefficient have to be considered for device
application environment.
2. Protection Features
In order to prevent overloading or thermal con-
dition from damaging the device,
APE8800A
has
internal thermal and current limiting functions
designed to protect the device. It will rapidly
shut off PMOS pass element during overload-
ing or over temperature condition.
3. Thermal Consideration
The power handling capability of the device will
be limited by maximum operation junction tem-
perature. The power dissipated by the device
will be estimated by PD = IOUT
×
(VIN-VOUT).
The power dissipation should be lower than the
maximum power dissipation listed in “Absolute
Maximum Ratings” section.
4. Shutdown Operation
The APE8800A is shutdown by pulling the
SHDN
input low, and turned on by driving the
SHDN
high. If this function is not used, the
SHDN
input should be tied to VIN to keep the regu-
lator on at all times (the
SHDN
must not be
left floating).
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A-POWER [ ADVANCED POWER ELECTRONICS CORP. ]
