500mA CMOS LDO Voltage Regulator
(Preliminary)
Application Hints
Like any low dropout regulator, SE5218 requires
external capacitors to ensure stability.
ensure performance.
The
external capacitors must be carefully selected to
SE5218
Thermal Considerations
It is important that the thermal limit of the package
is not exceeded.
thermal protection.
The SE5218 has built-in
When the thermal limit is
exceeded, the IC will enter protection, and V
OUT
will be pulled to ground. The power dissipation
for a given application can be calculated as
following:
The power dissipation (P
D
) is
P
D
= I
OUT
* [V
IN
– V
OUT
]
It
The thermal limit of the package is then limited to
P
D(MAX)
= [T
J
– T
A
]/Θ
JA
where T
J
is the junction
temperature, TA is the ambient temperature, and
Θ
JA
for SOT-23-5L is around 230°C/W for
SE5218. SE5218 is designed to enter thermal
protection at 150°C. For example, if T
A
is 25°C
then the maximum P
D
is limited to about 0.6W.
In other words, if I
OUT(MAX)
= 400mA, then [V
IN
–
V
OUT
] cannot exceed 1.5V.
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.
Output Capacitor
An output capacitor is required for stability.
must be placed no more than 1 cm away from the
V
OUT
pin, and connected directly between V
OUT
and GND pins. The inexpensive Electrolytic
capacitor is recommended. The minimum value is
1μF but may be increased without limit.
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. ]
