MP20046 – FAST TRANSIENT RESPONSE, 2A, LOW DROPOUT VOLTAGE REGULATOR

MP20046 Rev. 1.1

www.MonolithicPower.com

11

10/13/2010

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OPERATION

The MP20046 is a low dropout linear regulator

supplying up to 2A current. It is intended for use

in devices that require very low dropout voltage,

low quiescent, low noise and high PSRR such

as wireless LAN, battery powered equipment

and hand-held equipment.

The MP20046 uses an internal PMOS as the

pass element and features internal thermal

shutdown and internal current limit circuit.

Dropout Voltage

Dropout voltage is the minimum input to output

differential voltage required for the regulator to

maintain an output voltage within 100mV of its

nominal value. Because the PMOS pass

element behaves as a low-value resistor, the

dropout voltage of MP20046 is very low.

Shutdown

The MP20046 can be switched ON or OFF by a

should be tied to GND to keep the regulator

output always on if the application does not

require the shutdown feature. Do not float the

Current Limit

The MP20046 includes a current limit structure

which monitors and controls PMOS’s gate

voltage to limit the guaranteed maximum output

current to 3.3A.

Power Good

The power good pin is an open collector output

connected to OUT with a pull up resistor. It

monitors the output voltage, and if the output

voltage deceases below 83% of its regulation

point, the PG pin becomes low. Enlarging pull

up resistor or bypass capacitor will extend the

set up time of PG output.

Thermal Protection

Thermal protection turns off the PMOS when

the junction temperature exceeds +150ºC,

allowing the IC to cool. When the IC’s junction

temperature drops by 20ºC, the PMOS will be

turned on again. Thermal protection limits total

power dissipation in the MP20046. For reliable

operation, junction temperature should be

limited to 125 ºC maximum.

Load-Transient Considerations

The output response of load-transient consists

of a DC shift and transient response. Because

of the excellent load regulation of MP20046, the

DC shift is very small. For external circuit, the

output voltage transient depends on the output

capacitor’s value and the ESR. Increasing the

capacitance and decreasing the ESR will

improve the transient response.