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Date: 12/13/05 SP6213, SP6214 Micropower, SC-70, 100mA CMOS LDO Regulator © Copyright 2005 Sipex Corporation
General Overview
Enable/Shutdown Operation
The SP6213/4 is turned off by pulling the EN
pin low and turned on by pulling it high. If this
enable/shutdown feature is not required, EN
should be tied to V
IN
to keep the regulator
output on at all times.
Input Capacitor
Any good quality ceramic or tantalum capaci-
tor may be used at the input. A small capacitor
of about 1µF is required from V
IN
to GND if, for
instance, a battery is used as the input.
Output Capacitor
An output capacitor is required between V
OUT
and GND to prevent oscillation. The minimum
size of the output capacitor is a 0.47 µF
ceramic. The given datasheet values relate to
an IC with a ceramic output capacitor of 1µF.
Larger values make the IC more stable which
means an improvement of the regulator’s
transient response. For a lower output cur-
rent, the output capacitance can be chosen
smaller in order to have the same output
stability.
No Load Stability
The SP6213/4 will remain stable and in regu-
lation with no external load (other than the
internal voltage driver) unlike many other volt-
age regulators. This is especially important in
CMOS RAM keep-alive applications.
Thermal Considerations
The SP6213/4 is designed to provide 100 mA
of continuous current in a very tiny package.
Maximum power dissipation can be calcu-
lated based on the output current and the
voltage drop across the part. To determine
the maximum power dissipation of the pack-
age, use the junction-to-ambient thermal re-
sistance of the device and the following basic
equation:
P
D
= (T
J(max)
- T
A
) / θ
JA
T
J(max)
is the maximum junction temperature
of the die and is 125°C. T
A
is the ambient
operating temperature. θ
JA
is the junction-to-
ambient thermal resistance for the regulator
and is layout dependent. The actual power
dissipation of the regulator circuit can be
determined using one simple equation:
P
D
= (V
IN
- V
OUT
)*I
OUT
+ V
IN
*I
GND
Substituting P
D(max)
for P
D
and solving for the
operating conditions that are critical to the
application will give the maximum operating
conditions for the regulator circuit. For ex-
ample, if we are operating the SP6213/4 at
3.0V output at room temperature, with a mini-
mum footprint layout, we can determine the
maximum input voltage for a set output cur-
rent:
P
D(max)
= [(125°C -25°C) / (330°C/W)]
= 303 mW.
To prevent the device from entering thermal
shutdown, maximum power dissipation can
not be exceeded. Using the output voltage of
3.0V and an output current of 100 mA, the
maximum input voltage can be determined.
Ground pin current can be taken from the
electrical specifications table (0.135 mA at
100 mA). The maximum input voltage is de-
termined as follows:
303mW = (V
IN
– 3.0V)*100mA + V
IN
*0.135mA
After calculations, we find that the maximum
input voltage of a 3.0V application at 100mA
of output current in an SC-70-5 package is
6.02V.
THEORY OF OPERATION
