MP2497 – 3A, 50V, 100kHz STEP-DOWN CONVERTER

MP2497 Rev. 1.12

www.MonolithicPower.com

11

12/22/2011

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Programming the Short Circuit Current Limit

The hiccup current limit at output short

condition can be programmed to be lower by

in figure 4.

When output voltage is lower than 200mV, the

current limit is described by:

OUT _ SL

SENSE

S1

I

R

6.2 A R

100mV

×+

μ ×

=

(14)

The current limit at output short condition is:

S1

OUT _ SL

SENSE

100mV 6.2 A R

I

R

−μ ×

=

(15)

SW

ISP

ISN

200mV

6.2uA

Figure 4—Short Circuit Current Limit

PC Board Layout

The high frequency path (IN, SW and GND)

should be placed very close to the device with

short, direct and wide traces. The input

capacitor needs to be as close as possible to

the IN and GND pins. The external feedback

resistors should be placed next to the FB pin.

Keep the switching node SW short and away

from the feedback network.

External Bootstrap Diode

It is recommended that an external bootstrap

diode be added when the system has a 5V

fixed input or the power supply generates a 5V

output. This helps improve the efficiency of the

regulator. The bootstrap diode can be a low

cost one such as IN4148 or BAT54.

This diode is also recommended for high duty

cycle operation (when

O U T

I N

V

V

>65%) and high

MP2497

BS

SW

10nF

5V

Figure 5—External Bootstrap Diode

Design Example

Below is a design example following the

application guidelines for the specifications:

8 to 50V

5V

6V

100kHz

3A

The detailed application schematic is shown in

Figure 6.

The typical performance and circuit

waveforms have been shown in the Typical

Performance Characteristics section. For more

possible applications of this device, please refer

to related Evaluation Board Data Sheets.