Datasheet

LMR24210
SNVS738G –OCTOBER 2011–REVISED APRIL 2013 www.ti.com
If the output current I
OUT
is determined, by assuming that I
OUT
= I
L
, the higher and lower peak of I
LR
can be
determined. Beware that the higher peak of I
LR
should not be larger than the saturation current of the inductor
and current limits of the main and synchronous MOSFETs. Also, the lower peak of I
LR
must be positive if CCM
operation is required.
Figure 25. Inductor selection for V
OUT
= 3.3V
Figure 26. Inductor selection for V
OUT
= 0.8V
Figure 25 and Figure 26 show curves on inductor selection for various V
OUT
and R
ON
. For small R
ON
, according
to Equation 10, V
IN
is limited. Some curves are therefore limited as shown in the figures.
C
VCC
: The capacitor on the V
CC
output provides not only noise filtering and stability, but also prevents false
triggering of the V
CC
UVLO at the main MOSFET on/off transitions. C
VCC
should be no smaller than 680 nF for
stability, and should be a good quality, low ESR, ceramic capacitor.
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