ACT2113

Rev 3, 23-May-12

®

- 7 -

www.active-semi.com

Copyright © 2012 Active-Semi, Inc.

APPLICATIONS INFORMATION

Output Voltage Setting

Figure 1:

Output Voltage Setting

Figure 1 shows the connections for setting the

output voltage. Select the proper ratio of the two

Table 1:

Recommended Resistance Values

Inductor Selection

The inductor maintains a continuous current to the

output load. This inductor current has a ripple that is

dependent on the inductance value:

Higher inductance reduces the peak-to-peak ripple

current. The trade off for high inductance value is

the increase in inductor core size and series

resistance, and the reduction in current handling

capability. In general, select an inductance value L

based on ripple current requirement:

correspond to the peak-to-peak inductor ripple

current being 20~40%

of the maximum load

current.

With a selected inductor value the peak-to-peak

inductor current is estimated as:

The peak inductor current is estimated as:

The maximum output current is calculated as:

4.5A, as shown in Electrical Characteristics Table.

(3)

(

)

SW

IN

OUT

IN

OUT

PK

LPK

f

V

L

V

V

V

I

×

×

−

×

=

−

PK

LPK

LOADMAX

LPK

I

I

I

−

+

=

2

1

(4)

⎟

⎠

⎞

⎜

⎝

⎛

−

=

1

923

.

0

2

1

V

V

R

R

OUT

FB

FB

(1)

(2)

(

)

RIPPLE

LOADMAX

SW

IN

OUT

IN

OUT

K

I

f

V

V

V

V

L

_

×

=

(5)

PK

LPK

LIM

OUTMAX

I

2

1

I

I

_

_

=

R1

R2

5.0V

47kΩ

10.5kΩ

3.3V

27.4kΩ

10.5kΩ

2.5V

18kΩ

10.5kΩ

1.8V

10.2kΩ

10.5kΩ

1.2V

3.3kΩ

10.5kΩ

1.0V

1kΩ

10.5kΩ

Table 2:

Inductor Values Range and Typical Compensation

L

5.0V

8V ~ 18V

4.7µH ~ 10µH

330µF/10V

25kΩ

2.2nF

220PF

22µF/ Ceramic × 2

10kΩ

2.2nF

220PF

3.3V

6V ~ 18V

3.3µH ~ 8.2µH

330µF/10V

21kΩ

2.2nF

220PF

22µF/ Ceramic × 2

8.2kΩ

2.2nF

220PF

1.8V

4.5V ~ 8V

2.2µH ~ 6.8µH

470µF/10V

12kΩ

4.7nF

220PF

22µF/ Ceramic × 2

8.2kΩ

4.7nF

N/A

1.2V

4.5V ~ 6V

2µH ~ 6µH

470µF/10V

12kΩ

10nF

220PF

22µF/ Ceramic × 2

8.2kΩ

10nF

N/A

4.5V ~ 5.2V

1.5µH ~ 4.7µH

470µF/10V

10kΩ

10nF

220PF

22µF/ Ceramic × 2

8.2kΩ

10nF

N/A

1.0V