MP2490 – 1.5A, 36V, 700KHz STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT

MP2490 Rev. 0.92

www.MonolithicPower.com

10

4/23/2010

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Output Current Sensing

The output current can be sensed through the

DC resistance (DCR) of the inductor, as shown

in Figure 2a.

In Figure 2a, the output current limit is set as:

ab

OUT

b

RR

100mV

I

DCR

R

+

=×

Where DCR is the DC resistance of the inductor

winding.

In Figure 2a, it is desirable to keep

ab

S

ab

RR

L1

C

R

R

DCR

⋅

×=

+

If, there is no Rb:

×=

as

L1

RC

DCR

For more accurate sensing, use a more

accurate sense resistor, as in Figure 2b, where

the output current limit is set as:

OUT

SENSE

100mV

I

R

=

Figure 2—Current Sensing Methods