Micrel, Inc.

MIC2290

October 2007

9

M9999-101907

Input capacitor

A minimum 1µF ceramic capacitor is recommended for

designing

with

the

MIC2290.

Increasing

input

capacitance will improve performance and greater noise

immunity on the source. The input capacitor should be

as close as possible to the inductor and the MIC2290,

with short traces for good noise performance.

Feedback Resistors

The MIC2290 utilizes a feedback pin to compare the

output to an internal reference. The output voltage is

adjusted by selecting the appropriate feedback resistor

network values. The R2 resistor value must be less than

or equal to 5kΩ (R2 ≤ 5kΩ). The desired output voltage

can be calculated as follows:

⎟

⎠

⎞

⎜

⎝

⎛

+

×

=

1

R2

R1

V

V

REF

OUT

where VREF is equal to 1.24V.