The MAX603/MAX604 low-dropout, low quiescent current,
linear regulators supply 5V, 3.3V, or an adjustable
output for currents up to 500mA. They are available in a
1.8W SO package. Typical dropouts are 320mV at 5V
and 500mA, or 240mV at 3.3V and 200mA. Quiescent
currents are 15μA typ and 35μA max. Shutdown turns
off all circuitry and puts the regulator in a 2μA off mode.
A unique protection scheme limits reverse currents
when the input voltage falls below the output. Other features
include foldback current limiting and thermal
overload protection.
The output is preset at 3.3V for the MAX604 and 5V for
the MAX603. In addition, both devices employ Dual
Mode? operation, allowing user-adjustable outputs
from 1.25V to 11V using external resistors. The input
voltage supply range is 2.7V to 11.5V.
The MAX603/MAX604 feature a 500mA P-channel
MOSFET pass transistor. This transistor allows the
devices to draw less than 35μA over temperature, independent
of the output current. The supply current
remains low because the P-channel MOSFET pass transistor
draws no base currents (unlike the PNP transistors
of conventional bipolar linear regulators). Also,
when the input-to-output voltage differential becomes
small, the internal P-channel MOSFET does not suffer
from excessive base current losses that occur with saturated
PNP transistors.
________________________Applications
5V and 3.3V Regulators
1.25V to 11V Adjustable Regulators
Battery-Powered Devices
Pagers and Cellular Phones
Portable Instruments
Solar-Powered Instruments