Application information

STBB1XX

14/21

Doc ID 15474 Rev 5

The minimum inductor value for the application is the higher between Equation 2 and

Equation 3

. In addition to the inductance value the maximum current the inductor can

handle must be calculated in order to avoid saturation.

Equation 4

Equation 5

Where

η is the estimated efficiency of STBB1. The maximum of the two values above must

be considered when selecting the inductor.

8.3

Input and output capacitor selection

It is recommended to use ceramic capacitors with low ESR as input and output capacitors in

order to filter any disturbance present in the input line and to obtain stable operation.

Minimum values of 10 µF for both capacitors are needed to achieve good behavior of the

device.

The input capacitor must be placed as close as possible to the device.

L

fs

VIN

2

)

VOUT

VIN

(

VOUT

)

/

I

(

I

MAX

MAX

OUT

BUCK

PEAK

×

×

×

−

×

+

η

=

−

L

fs

VOUT

2

)

VIN

VOUT

(

VIN

VIN

I

VOUT

I

MIN

MIN

MIN

OUT

BOOST

PEAK

×

×

×

−

×

+

×

η

×

=

−