MIC39500/39501
with an input as low as 3.0V or 2.5V respectively. This gives
PNP-based regulators a distinct advantage over older, NPN-
based linear regulators.
A typical NPN regulator does not have the headroom to do
this conversion.
Minimum Load Current
The MIC39500/1 regulator is specified between finite loads.
If the output current is too small, leakage currents dominate
and the output voltage rises. A 10mA minimum load current
is necessary for proper regulation.
Error Flag
Micrel
The MIC39501 version features an error flag circuit which
monitors the output voltage and signals an error condition
when the voltage 5% below the nominal output voltage. The
error flag is an open-collector output that can sink 10mA
during a fault condition.
Low output voltage can be caused by a number of problems,
including an overcurrent fault (device in current limit) or low
input voltage. The flag is inoperative during overtemperature
shutdown.
When the error flag is not used, it is best to leave it open.
The flag pin can be tied directly to pin 4, the output pin.
Enable Input
The MIC39501 version features an enable input for on/off
control of the device. Its shutdown state draws “zero” cur-
rent (only microamperes of leakage). The enable input is
TTL/CMOS compatible for simple logic interface, but can be
connected to up to 20V.
M9999-082605-B
8
August 2005
MICREL [ MICREL SEMICONDUCTOR ]
