MP5021 – 12V, 7

MP5021 Rev. 1.1

www.MonolithicPower.com

17

1/30/2013

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© 2013 MPS. All Rights Reserved.

APPLICATION INFORMATION

The MP5021 current limit value should exceed

the normal maximum load current, allowing the

tolerances in the current sense value. Estimate

the current limit from the following equation:

4

limit

SET

0.6(V)

I

=

20 10 (A)

R

××

The table below gives the bench results from the

evaluation board.

Current Limit vs. Current Limit Resistor

Current Limit Resistor (kΩ)

7.5

10

20

Current Limit (A)

15.9

12.1

6.08

0

2

4

6

8

10

12

14

16

18

20

6 1626 3646 5666 7686 96

Current Monitor

MP5021 provides a power-MOSFET-current

ground to set the gain of the output as per the

following equation:

5

I

IIMON

10

For example:

PCB Layout Guide

Use the following layout guidelines for the

MP5021:

1. Place the high-current paths (GND, IN, and

OUT) very close to the device using short,

direct, and wide traces.

2. Place the input capacitors as close to the IN

and GND pins as possible.

3. Place the external feedback resistors next to

the FB pin. Avoid placing any vias on the FB

trace

4. Place the Schottky diode close to the OUT

and GND pins. This Schottky diode can limit

the Vout negative excursion at the OUT pin

when the load current shuts off.

5. Connect the IN and GND pads to large

copper to achieve better thermal performance.

6. Place a small capacitor, (for example 1nF)

directly adjacent the VIN and GND pins to

minimize transients on the input supply line.

7. Put vias in the thermal pad and provide a

large copper area near the IN pin to improve

thermal performance.

VIN

1

2

3

4

5

6

7

8

9

20

19

18

17

16

15

14

13

12

OUT

OUT

OUT

OUT

OUT

OUT

OUT

OUT

PD

PG

FB

VIN

VIN

VIN

VIN

VIN

VIN

VIN

EN

AUTO

ISET

SS

GND

IMON

FLTB

VOUT

GND

ENTM

R3

TIMER

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