MP20049 – ULTRA-LOW NOISE, HIGH PSRR 150mA LINEAR REGULATOR IN 0.8x0.8mm WLCSP

MP20049 Rev. 1.1

www.MonolithicPower.com

8

10/22/2010

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OPERATION

The MP20049 is an ultra low noise, low

dropout, low quiescent current and high PSRR

linear

regulator

for

space-restricted

applications. It is intended for use in devices

that require very low voltage, and ultra-small

footprint, such as mobile phone and MP3

players.

The MP20049 uses an internal PMOS as the

pass elements and features internal thermal

shutdown and internal current limit circuits.

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. It determines the available end-

of-life

battery

voltage

in

battery-powered

systems. For the P-channel MOSFET pass

element, the dropout voltage is a function of

drain to source on resistance. Because the P-

channel MOSFET pass element behaves as a

low-value resistor, the dropout voltage of

MP20049 is very low.

Under Voltage Lockout

The MP20049 has an internal under-voltage

lockout circuit that disables the device when the

input voltage is less than approximately 2.3V.

This ensures that the input and the output of the

MP20049 behave in a predictable manner

during input power-up.

Enable ON/Off

The MP20049 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

should be tied to VIN to keep the regulator

output always on if the application does not

require the shutdown feature.

Do not float the EN pin.

Current Limit and Thermal Protection

The MP20049 includes an independent current

limit structure which monitors and controls the

P-channel MOSFET’s gate voltage to limit the

guaranteed maximum output current to 150mA.

Thermal protection turns off the P-channel

MOSFET

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

MP20049. For reliable operation, junction

temperature should be limited to 125ºC

maximum.