DIO6970

www.dioo.com

© 2018 DIOO MICROCIRCUITS CO., LTD

DIO6970• Rev. 1.1

 

Output capacitor COUT

The output capacitor is selected to handle the output ripple noise requirements. Both steady state ripple and

transient requirements must be taken into consideration when selecting this capacitor. For the best

performance, it is recommended to use X5R or better grade ceramic capacitor greater than 22µF capacitance.

Output inductor L

There are several considerations in choosing this inductor.

1) Choose the inductance to provide the desired ripple current. It is suggested to choose the ripple current to

be about 40% of the maximum output current. The inductance is calculated as:

L

=

%

40

)

/

1

(

,

,







MAX

OUT

SW

MAX

IN

OUT

OUT

I

F

V

V

V

where Fsw is the switching frequency and IOUT,MAX is the maximum load current.

The DIO6970 regulator IC is quite tolerant of different ripple current amplitude. Consequently, the final

choice of inductance can be slightly off the calculation value without significantly impacting the performance.

2) The saturation current rating of the inductor must be selected to be greater than the peak inductor current

under full load conditions.

ISAT,MIN>IOUT,MAX

+

L

F

V

V

V

SW

MAX

IN

OUT

OUT







2

)

/

1

(

,

3) The DCR of the inductor and the core loss at the switching frequency must be low enough to achieve the

desired efficiency requirement. It is desirable to choose an inductor with DCR<50mΩ to achieve a good

overall efficiency.

External Bootstrap Cap

This capacitor provides the gate driver voltage for internal high side MOSFET. A 100nF low ESR ceramic

capacitor connected between BS pin and SW pin is recommended.

Load Transient Considerations

The DIO6970 regulator IC integrates the compensation components to achieve good stability and fast

transient responses. In some applications, adding a 22pF ceramic cap in parallel with R1 may further speed up

the load transient responses and is thus recommended for applications with large load transient.