MIC5203 Datasheet, PDF (7/7 Pages) Micrel Semiconductor – μCap™ 80mA Low-Dropout Voltage Regulator

MIC5203
Applications Information
Input Capacitor
A 0.1µF capacitor should be placed from IN to GND if there
is more than 10 inches of wire between the input and the ac
filter capacitor or when a battery is used as the input.
Output Capacitor
Typical PNP based regulators require an output capacitor to
prevent oscillation. The MIC5203 is ultrastable, requiring only
0.47µF of output capacitance for stability. The regulator is
stable with all types of capacitors, including the tiny, low-ESR
ceramic chip capacitors. The output capacitor value can be
increased without limit to improve transient response.
The capacitor should have a resonant frequency above
500kHz. Ceramic capacitors work, but some dielectrics have
poor temperature coefficients, which will affect the value of
the output capacitor over temperature. Tantalum capacitors
are much more stable over temperature, but typically are
larger and more expensive. Aluminum electrolytic capacitors
Micrel
will also work, but they have electrolytes that freeze at about
–30C°. Tantalum or ceramic capacitors are recommended
for operation below –25C°.
No-Load Stability
The MIC5203 will remain stable and in regulation with no load
(other than the internal voltage divider) unlike many other
voltage regulators. This is especially important in CMOS
RAM keep-alive applications.
Enable Input
The MIC5203 features nearly zero off-mode current. When
EN (enable input) is held below 0.6V, all internal circuitry is
powered off. Pulling EN high (over 2.0V) re-enables the
device and allows operation. EN draws a small amount of
current, typically 15µA. While the logic threshold is TTL/
CMOS compatible, EN may be pulled as high as 20V,
independent of V_IN.
3
December 1998
3-147