MP2490 – 1.5A, 36V, 700kHz STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT
MP2490 Rev. 1.0 www.MonolithicPower.com 10
4/9/2014 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
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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
