MP1522 – 25V STEP-UP CONVERTER IN A SOT23-5 PACKAGE

MP1522 Rev. 1.9

www.MonolithicPower.com

5

12/9/2005

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Diode

The high switching frequencies of the MP1522

require the use of fast recovery or Schottky

barrier diodes. In low voltage applications

Schottky barrier diodes are recommended for

maximum efficiency. The reverse breakdown

voltage should be approximately 1.5X the

output voltage.

Printed Circuit Board Layout

The printed circuit board layout is important in

order to minimize noise and prevent erratic

operation. Keep the ground leads short and

robust with minimum lead lengths between the

input and output capacitors and ground. Place

the feedback resistive voltage divider as close

to FB as possible to prevent switching noise

injection into FB. The use of surface mount

capacitors with their low ESL is required to

minimize noise at the MP1522. Use separate

power and quiet ground planes connected

together at a single point whenever possible to

Table 1—Output Current vs. Input Voltage

3.3

5

67

3.3

12

28

3.3

18

15

3.3

25

10

5

12

44

5

18

32

5

25

19

10

12

122

10

18

75

10

25

51

MP1522_TAC_F02

FB

SW

GND

EN

2

4

3

5

1

OFF ON

20V

3.3V

C2

1nF

D1

RB751

Figure 2—Typical Boost Application