FP6166

This datasheet contains new product information. Feeling Technology reserves the rights to modify the product specification without notice.

No liability is assumed as a result of the use of this product. No rights under any patent accompany the sales of the product.

Rev. 0.65

11/19

Application Information

Input capacitor Selection

The input capacitor must be connected to the VIN pin and GND pin of the FP6166 to maintain

steady input voltage and filter out the pulsing input current. The voltage rating of input capacitor must

be greater than maximum input voltage plus ripple voltage.

In switch mode, the input current is discontinuous in a buck converter. The source current of the

high-side MOSFET is a square wave. To prevent large voltage transients, a low ESR input capacitor

sized for the maximum RMS current must be used. The RMS value of input capacitor current can be

calculated by:

















IN

O

IN

O

MAX

_

O

RMS

V

V

1

V

V

I

I

Inductor Selection

The value of the inductor is selected based on the desired ripple current. Large inductance gives

low inductor ripple current and small inductance result in high ripple current. However, the larger value

inductor has a larger physical size, higher series resistance, and/or lower saturation current. In

experience, the value is to allow the peak-to-peak ripple current in the inductor to be 10%~20%

maximum load current. The inductance value can be calculated by:



IN

O

O

O

IN

IN

O

L

O

IN

V

V

I

%)

20

~

%

10

(

2

f

)

V

V

(

V

V

I

f

)

V

V

(

L

















The inductor ripple current can be calculated by:























IN

O

O

L

V

V

1

L

f

V

I

Choose an inductor that does not saturate under the worst-case load conditions, which is the

load current plus half the peak-to-peak inductor ripple current, even at the highest operating

temperature. The peak inductor current is:

2

I

I

I

L

O

PEAK

_

L





