MP2270 – 1.8A, 24V, 700KHz STEP-DOWN CONVERTER

MP2270 Rev. 1.1

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9

4/16/2010

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External Bootstrap Diode

An external bootstrap diode may enhance the

efficiency of the regulator, the applicable

conditions of external BST diode are:

Duty cycle is high: D=

IN

OUT

V

V

>65%

In these cases, an external BST diode is

recommended from the output of the voltage

regulator to BST pin, as shown in Fig.2

MP2270

SW

BST

C

L

BST

C

5V or 3.3V

OUT

External BST Diode

IN4148

Figure 2—Add Optional External Bootstrap

Diode to Enhance Efficiency

The recommended external BST diode is IN4148,

and the BST cap is 0.1~1µF.

Table 2—Suggested Surface Mount Inductors

Manufacturer

Part Number

Inductance(µH)

Max DCR(Ω)

Current Rating

(A)

Dimensions

L x W x H (mm

Wurth Electronics

7447785004

4.7

0.060

2.5

5.9 x 6.2 x 3.3

Toko

A916CY-4R7M

4.7

0.026

2.5

6.2 x 6.3 x 3.5

Coiltronics

DR73-4R7

4.7

0.03

3

6.0 x 7.6 x 3.5