Advanced Power
Electronics Corp.
APE8805
Block Diagram
RSEN
VIN
VOUT
PMOS
Current
Limit
Error
Amp
R1
R2
_
+
Thermal
Shutdown
Vref 1.2V
GND
Figure 3. Block Diagram of APE8805
Application Information
The APE8805 series are low dropout linear
regulators that could provide 600mA output
current at dropout voltage about 600mV. Besides,
current limit and on chip thermal shutdown
features provide protection against any
combination of overload or ambient temperature
that could exceed junction temperature.
ESR of output capacitor is very important
beca- use it generates a zero to provide
phase lead for loop stability.
There are no requirements for the ESR on
the input capacitor, but its voltage and
temperature
considered
environment.
coefficient
for device
have
to
be
application
1.Output and Input Capacitor
The APE8805 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 provides to improve
transition 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
to ground for transient stability. The APE8805
is designed to be stable with low ESR ceramic
capacitors and higher values of capacitors and
ESR could improve output stability. So the
2.Protection Features
In order to prevent overloading or thermal
cond- ition from damaging device, APE8805
regulator has internal thermal and current
limiting functions designed to protect the
device. It will rapidly shut off PMOS pass
element during overloading or over
temperature condition.
3.Thermal Consideration
The power handling capability of the device
will be limited by maximum operation
junction temp- erature (125°C). 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.
4/9
A-POWER [ ADVANCED POWER ELECTRONICS CORP. ]
