4
APE8805
Advanced Power
Electronics Corp.
BLOCK DIAGRAM
Error
Amp
Current
Limit
Thermal
Shutdown
_
__
_+
++
+
Vref 1.2V
VIN VOUT
GND
RSEN
PMOS
R1
R2
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.
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
tantalum) 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 30mΩΩΩΩ
to 50mΩΩΩΩ 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
ESR of output capacitor is very important because
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 coefficient have to be considered
for device application environment.
2.PROTECTION FEATURES
In order to prevent overloading or thermal condition
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
temperature (125°C). The power dissipated by the
device will be estimated by
PD = IOUT x (VIN-VOUT).
The power dissipation should be lower than the
maximum power dissipation listed in
“Absolute Maximum Ratings” section.