Si786

Vishay Siliconix

www.vishay.com

14

Document Number: 70189

S-40807—Rev. J, 26-Apr-04

Both minimum capacitance and maximum ESR requirements

must be met. In order to get the low ESR, a capacitance value

of two to three times greater than the required minimum may

be necessary.

The equation for output ripple in continuous current mode is:

1

2

P xf

The equations for capacitive and resistive components of the

ripple in pulse-skipping mode are:

as follows:

1

)

1

Lower Voltage Input

The application circuit shown here can be easily modified to

work with 5.5-V to 12-V input voltages. Oscillation frequency

should be set at 200 kHz and increase the output capacitance

to 660 mF on the 5-V output to maintain stable performance up

to 2 A of load current. Operation on the 3.3-V supply will not be

affected by this reduced input voltage.