DIO6905

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DIO6905 • Rev. 1.8

- 10 -

Application Information

Setting the output voltage

The external resistor divider sets the output voltage. Select the feedback resistor R1 which reduces the VOUT

leakage current, typically between 40 kΩ to 200 kΩ. There is not strict requirement on the feedback resistor. R1 >

10 kΩ is reasoned for most application. R2 can be calculated with Equation (2):

1

-

0.6

V

R1

=

R2

OUT

(2)

The feedback circuit is shown as Figure 18:

Figure 18. Feedback network

Table 1 lists the recommended resistor’s values for common output voltages:

Table 1. Resistor values for common output voltages

Selecting the inductor

Most applications work best with a 1 µH to 2.2 µH inductor. For highest efficiency, choose an inductor with a DC

resistance less than 15 mΩ.

A high-frequency switch-mode power supply with a magnetic device has strong electronic magnetic inference.

Any unshielded power inductors should be avoided. Metal alloy or multiplayer chip power inductors are ideal

shielded inductors for the application because they can decrease the influence effectively. Table 2 lists some

recommended inductors.

Table 2. Recommended inductors

Manufacturer P/N

Inductance (μH )

Manufacturer

PIFE25201B-1R0MS

1.0

CYNTEC CO. LTD.

1239AS-H-1R0M

1.0

Tokyo

744 777 002

2.2

Wurth

VOUT (V)

R1 (kΩ)

R2 (kΩ)

1.0

200 (1%)

300 (1%)

1.2

200 (1%)

200 (1%)

1.8

200 (1%)

100 (1%)

2.5

200 (1%)

63.2 (1%)

3.3

200 (1%)

44.2 (1%)