MP24971 –1.5A, 50V, 100kHz, 5V FIXED OUTPUT STEP-DOWN CONVERTER

MP24971 Rev. 1.01

www.MonolithicPower.com

12

1/6/2012

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2012 MPS. All Rights Reserved.

PC Board Layout

The high frequency paths for VIN, SW and

GND should be routed very close to the device

with short, direct, and wide traces. Place the

input capacitor as close as possible to the IN

and GND pins. Place the external feedback

resistors next to the FB pin. Keep the switching

node SW short and away from the feedback

network.

External Bootstrap Diode

An external bootstrap diode helps improve the

efficiency of the regulator when the system has

a 5V fixed input or the power supply generates

a 5V output. The bootstrap diode can be low-

cost, such as an IN4148 or a BAT54.

Add a diode for high duty-cycle operation (when

OUT

IN

V

V

>65%).

MP24971

BS

SW

10nF

5V

Figure 5—External Bootstrap Diode

Design Example

Below is a sample design that follows the

application guidelines for the specifications

below:

Parameter

Symbol

Value

Units

Input Voltage

8 - 50

V

Output Voltage

5

V

Output Current Limit

1.5

A

Output OVP

6

V

Figure 6 shows the detailed application

schematic.

The

Typical

Performance

Characteristics

performance

and

circuit

waveforms are all based on this design. For

additional implentations, consult the Evaluation

Board Data Sheets.

+

L1

33µH

MP24971

SW

VOC

ISP

ISN

VOS

BST

VIN

GND

GND

0.1µF

GND

Vcc

NS

402kO

B360A

22µF

100µF

100mO

NS

0.1µF

1kO

1kO

10nF

10nF

0O

0O

0.1µF

0.1µF

100µ F

2.2µF

100O

165O

Figure 6—Detailed Sample Application Schematic