500mA CMOS LDO Voltage Regulator
(Preliminary)
SE5218
Application Hints
Thermal Considerations
Like any low dropout regulator, SE5218 requires
It is important that the thermal limit of the package
external capacitors to ensure stability.
The
is not exceeded. The SE5218 has built-in
external capacitors must be carefully selected to
ensure performance.
thermal protection. When the thermal limit is
exceeded, the IC will enter protection, and VOUT
will be pulled to ground. The power dissipation
for a given application can be calculated as
following:
Input Capacitor
An input capacitor of at least 1μF is required. The
inexpensive Electrolytic capacitor is preferred.
The value can be increased without upper limit.
The power dissipation (PD) is
PD = IOUT * [VIN – VOUT
]
Output Capacitor
An output capacitor is required for stability. It
must be placed no more than 1 cm away from the
VOUT pin, and connected directly between VOUT
and GND pins. The inexpensive Electrolytic
capacitor is recommended. The minimum value is
1μF but may be increased without limit.
The thermal limit of the package is then limited to
PD(MAX) = [TJ – TA]/ΘJA where TJ is the junction
temperature, TA is the ambient temperature, and
ΘJA for SOT-23-5L is around 230°C/W for
SE5218. SE5218 is designed to enter thermal
protection at 150°C. For example, if TA is 25°C
then the maximum PD is limited to about 0.6W.
In other words, if IOUT(MAX) = 400mA, then [VIN
OUT] cannot exceed 1.5V.
–
V
Revision 12/5/2008
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2005. • www.seawardinc.com.cn • Page 6
SEAWARD [ Seaward Electronics Inc. ]
