MP6401 – 300mA LDO LINEAR REGULATOR WITH INTEGRATED RESET IC

MP6401 Rev. 1.0

www.MonolithicPower.com

11

9/7/2012

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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

output voltage drops below the standard

microprocessor supply threshold.

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

ADJ connection is shown in Fig 3.

2.5V to 5.5V

IN

OUT

ADJ

EN

GND

MP6401

R1

R2

Figure 3—Output Voltage Adjusted with

Resistor Divider

Reset Function

The reset circuit monitors the OUT voltage.

threshold. Two OUT voltage thresholds (-7.5%

power-down, and brownout conditions will make

asserts when the input and output voltage below

low logic. When the assert trigger condition is

time. Four options of reset delay-time (see Table

3) can be selected.

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.

Reverse Leakage Protection

the reverse leakage current from OUT to IN.

hold logic high, the monitor circuit turns off the

pass element and its parasitic diode. Typically the

reverse leakage current through pass element

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

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.

MP6401

IN

OUT

EN

Removable

MEMORY

uP

3.3uF

Backup

Battery

Figure 4— Maintain Memory with Backup

Battery

Current Limit

The MP6401 includes a current limit structure

which monitors and controls pass element gate

voltage limiting the guaranteed maximum output

current to 500mA.