MP2499– INTEGRATED 100V LOAD DUMP PROTECTION, 2A STEP DOWN REGULATOR

MP2499 Rev. 0.91

www.MonolithicPower.com

11

11/24/2010

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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

⋅

×=

+

For more accurate sensing, use a more

accurate (1% or less) sense resistor, as in

Figure 2b, where the output current limit is set

as:

OUT

SENSE

100mV

I

R

=

Cs

L1

L1

DCR

SW

ISP

ISN

SW

ISP

ISN

(a)

(b)

Figure 2—Current Sensing Methods