Dual 200mA CMOS
LDO Voltage Regulator
(Preliminary)
Application Hints
Like any low dropout regulator, SE5221 requires
external capacitors to ensure stability.
ensure performance.
The
external capacitors must be carefully selected to
SE5221
Thermal Considerations
It is important that the thermal limit of the package
is not exceeded.
thermal protection.
The SE5221 has built-in
When the thermal limit is
exceeded, the IC will enter protection, and V
OUT
will be gradually pulled to ground as load
continued to increase. 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-23-6 is around 230°C/W for SE5221.
SE5221 is designed to enter thermal protection at
120°C.
For example, if T
A
is 25°C then the
maximum P
D
is limited to about 0.4W. In other
words, if I
OUT(MAX)
= 200mA, then [V
IN
– V
OUT
]
cannot exceed 2V.
Input Capacitor
An input capacitor of at least 1μF is required.
Electrolytic or Ceramic or Tantalum can be used.
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.
Electrolytic or Ceramic or
Tantalum can be used. The minimum value is
1μF but may be increased without limit.
Revision 9/4/2008
Preliminary and all contents are subject to change without prior notice
© Seaward Electronics Inc., 2007. • www.seawardinc.com • Page 6
SEAWARD [ Seaward Electronics Inc. ]
