MP20249 – DUAL, ULTRA-LOW NOISE, HIGH PSRR 200mA LINEAR REGULATOR

MP20249 Rev. 1.0

www.MonolithicPower.com

11

12/15/2010

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2010 MPS. All Rights Reserved.

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

MP20249 to ground with a large ground plane

will help the channel heat away.

Input Capacitor Selection

Using a capacitor whose value is >1µF on the

MP20249 input and the amount of capacitance

can be increased without limit. 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 MP20249 is designed specifically to work

with very low ESR ceramic output capacitor and

benefit applications with space limitation.

Output capacitor of larger values will help to

improve load transient response and reduce

noise with the drawback of increased size. For

the application circuit, the MP20249 requires a

minimum capacitance of 0.7uF with an ESR of

1Ω or less.

Output Noise and PSRR

In the MP20249 device, each channel has an

internal 50pF bypass capacitor with new

innovative structure that reduces output noises

greatly. Therefore, space-limited applications

do not need to use external bypass capacitors.

The power supply rejection is 65dB at 10kHz

and 55dB at 100kHz.