MP6401 – 300mA LDO LINEAR REGULATOR WITH INTEGRATED RESET IC
OPERATION
The MP6401 integrates a low noise, low dropout,
low quiescent current linear regulator and a
microprocessor reset circuit. It operates from a
2.5V to 5.5V input voltage and regulates the fixed
output voltage with 2% accuracy at 1.8V, 2.5V,
3.3V or adjustable value. The MP6401 can supply
to 300mA of load current. The internal reset
circuit is used to monitor the regulator output
EN Shutdown
The MP6401 can be switched ON or OFF by a
logic input at the EN pin. A high voltage at this pin
will turn the device on. When the EN pin is low,
the regulator output is off and the supply current
is reduced. Generally, the EN pin should be tied
to IN to keep the regulator output always on. Do
not float the EN pin.
voltage. The
output voltage drops below the standard
microprocessor supply threshold.
asserts when the regulator
RESET
Reverse Leakage Protection
An internal circuit monitors VIN and VOUT to control
the reverse leakage current from OUT to IN.
While VIN decreases lower than VOUT and EN still
hold logic high, the monitor circuit turns off the
pass element and its parasitic diode. Typically the
reverse leakage current through pass element
Linear Regulator
The MP6401 can output a fixed voltage (1.8V,
2.5V, 3.3V options) or adjustable voltage which
ranges from 1.25V to 5V with 2.0% accuracy by
operating from a +2.5V to +5.5V input. The
MP6401 can supply up to 300mA of load current.
When ADJ is connected to GND, a fixed output
voltage is selected. Connecting ADJ pin to the tap
of external resistor divider from the OUT to GND,
adjustable output voltage is selected. The typical
decreases to 0.1uA.
deasserts until VIN
RESET
returns greater than VOUT and VOUT is higher than
its preset threshold.
MP6401 also can work with backup battery at
OUT after input power supply is removed as
shown in Fig 4. When input power supply is
ADJ connection is shown in Fig 3.
removed,
asserts. The backup battery
RESET
2.5V to 5.5V
will power the device through two external diodes
and typically the current from OUT to ground is
40uA. So, the power supply removing does not
erase RAM content if the voltage of backup
battery is greater than memory’s standby
specification. The backup battery can be replaced
by a super-cap, while the diode connected with
battery is changed to a current-limiting resistor.
IN
OUT
MP6401
R1
R2
ADJ
EN
GND
Figure 3—Output Voltage Adjusted with
Resistor Divider
Removable
IN
MP6401
OUT
Reset Function
3.3uF
The reset circuit monitors the OUT voltage.
Backup
Battery
uP
MEMORY
asserts while OUT voltage falls below its
RESET
EN
threshold. Two OUT voltage thresholds (-7.5%
and -12.5%) are available. The power-up,
power-down, and brownout conditions will make
Figure 4— Maintain Memory with Backup
Battery
Current Limit
asserted. So MP6401 monitor circuit
RESET
could right control the microprocessor.
RESET
The MP6401 includes a current limit structure
which monitors and controls pass element gate
voltage limiting the guaranteed maximum output
current to 500mA.
asserts when the input and output voltage below
their thresholds. asserts when EN is a
RESET
low logic. When the assert trigger condition is
removed, will deassert after a fixed delay
RESET
time. Four options of reset delay-time (see Table
3) can be selected.
MP6401 Rev. 1.0
9/7/2012
www.MonolithicPower.com
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© 2012 MPS. All Rights Reserved.
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