MP20048 – CAPACITOR-FREE, 250mA, LOW DROPOUT VOLTAGE REGULATOR

MP20048 Rev. 0.91

www.MonolithicPower.com

8

4/6/2010

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BLOCK DIAGRAM

Bandgap

+

+

Ref

Charge

Pump

Thermal

Protection

Current

Limit

Error

Amp

Error Amp

GND

EN

IN

OUT

4k

FB

Figure1—Functional Block Diagram

OPERATION

The MP20048 is a kind of new low-dropout

(LDO) voltage regulators which uses an NMOS

as the pass element in a voltage-follower

configuration. The highlight of this topology is

the stability even without outside capacitor. It

can get any value of output between 1.234V to

5V.

The MP20048 uses an advanced BICMOS

process to yield high precision. It also delivers

very low dropout voltages and low ground pin

current and features the thermal-off and current

limit block to protect the devices from damage.

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 NMOS pass

element behaves as a low-value resistor, the

dropout voltage of MP20048 is very low.

Enable Pin and Shutdown

The MP20048 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. The EN pin

output always on if the application does not

require the shutdown feature. Do not float the

EN pin.

Current Limit

The MP20048 includes a current limit structure

which monitors and controls NMOS’s gate

voltage to limit the guaranteed maximum output

current to 450mA.

Thermal Protection

Thermal protection turns off the NMOS when

the junction temperature exceeds +140ºC,

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

temperature drops by 10ºC, the NMOS will be

turned on again. Thermal protection limits total

power dissipation in the MP20048. For reliable

operation, junction temperature should be

limited to 125 ºC maximum.