Detailed Description
The MAX6329/MAX6349 are low-dropout, low-quies-
cent current linear regulators with integrated micro-
processor reset circuits. The devices drive loads up to
150mA and are available with preset output voltages of
+3.3V, +2.5V, or +1.8V. The internal reset circuit moni-
tors the regulator output voltage and asserts the reset
output when the regulator output is below the micro-
processor supply tolerance.
Regulator
The regulator core operates with an input voltage range
of +2.5V to +5.5V. The output voltage is offered with
three fixed voltage options (+3.3V, +2.5V, and +1.8V) for
the MAX6329 and MAX6349. Enable the fixed voltage
output by connecting SET to ground. The
MAX6329/MAX6349 offer an adjustable output voltage
that is implemented with an external resistor-divider net-
work connected to OUT, SET, and GND (Figure 1). SET
must be connected to either GND or the external divider.
The MAX6329/MAX6349 automatically determine the
feedback path depending on the voltage seen at SET.
Featured characteristics include ultra-low quiescent cur-
rent and low dropout voltage. The Typical Operating
Circuit shows a typical connection for the MAX6329.
OUT is an internally regulated low dropout (LDO) linear
regulator that powers a microprocessor.
Reset Circuit
The reset supervisor circuit is fully integrated in the
MAX6329/MAX6349 and uses the same reference volt-
age as the regulator. Two supply tolerance reset thresh-
olds, -5% and -10%, are provided for each type of
device:
MAX6329/MAX6349
150mA, SOT23, Low Dropout Linear Regulators
with Internal Microprocessor Reset Circuit
6 _______________________________________________________________________________________
Pin Description
PIN NAME DESCRIPTION
1 IN Regulator Input. Supply voltage can range from +2.5V to +5.5V.
2 GND
Ground. This pin also functions as a heatsink. Solder to large pads or the circuit board ground plane to
maximize thermal dissipation.
SHDN
(MAX6329 Only) Active-Low Shutdown Input. A logic low reduces the supply current to < 1µA. Connect
3
MR
(MAX6349 Only) Active-Low Manual Reset Input. A logic low forces a reset. Reset remains asserted for
the duration of the reset timeout period after MR transitions from low to high. Leave unconnected or
connect to V
OUT
if not used. MR has an internal pullup resistor of 20kΩ (typ) to OUT.
RESET
Active-Low Reset Output. RESET remains low while V
OUT
is below the reset threshold or while MR is
held low. RESET remains low for the duration of the reset timeout period after the reset conditions are
terminated.
4
RESET
Active-High Reset Output. RESET remains high while V
OUT
is below the reset threshold or while MR is
held low. RESET remains high for the duration of the reset timeout period after the reset conditions are
terminated.
5 SET
Feedback Input for Setting the Output Voltage. Connect to GND to set the output voltage to the preset
fixed value (+3.3V, +2.5V, or +1.8V). Connect to an external resistor-divider network for adjustable
output operation.
6 OUT
Regulator Output. Fixed (+3.3V, +2.5V, or +1.8V) or adjustable (+1.23V to +5.0V). Sources up to
150mA. Bypass with a 1µF minimum capacitor for full rated performance.
