MP2009-ULTRA LOW NOISE, LOW DROPOUT,120mA LINEAR REGULATOR

MP2009 Rev. 1.2

www.MonolithicPower.com

12

12/18/2013

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APPLICATION INFORMATION

Power Dissipation

The power dissipation for any package depends

on the thermal resistance of the case and circuit

board, the temperature difference between the

junction and ambient air, and the rate of airflow.

The power dissipation across the device can be

represented by the equation:

The

allowable

power

dissipation

can

be

calculated using the following equation:

difference

between

the

junction

and

the

resistance from the junction to the ambient

environment. Connecting the GND pin of

MP2009 to ground with a large ground plane will

help the channel heat away.

Output Noise and PSRR

For the MP2009, an internal 50pF bypass

capacitor with new innovative structure reduces

output noises greatly. It does not need external

bypass capacitor for space-limiting applications.

The power supply rejection is 75dB at 10kHz and

55dB at 100kHz. (See the PSRR vs. Frequency

graph

in

the

Typical

Performance

Characteristics).

Input Capacitor Selection

Use a 1µF capacitor on the input of the MP2009.

Larger values will help to improve line transient

response with the drawback of increased size.

Ceramic

capacitors

are

preferred,

but

tantalum

capacitors may also suffice.

Output Capacitor Selection

The MP2009 is designed specifically to work with

very low ESR ceramic output capacitor in space-

limiting and performance consideration. Output

capacitor of larger values will help to improve

load transient response and reduce noise with

the drawback of increased size. A 1µF ceramic

capacitor with ESR lower than 3Ω is sufficient for

the MP2009 application circuit. (See the Region

Typical Performance Characteristics)