R1211D002B RICOH [RICOH electronics devices division], R1211D002B Datasheet - Page 11

• Manufacturer Part Number: R1211D002B
• Description: STEP-UP DC/DC CONTROLLER
• Manufacturer: RICOH [RICOH electronics devices division]

continuous. The continuous current through the inductor is described as Iconst, then,
follows:
and external components should be selected.
components is not included. The actual maximum output current is between 50% and 80% of the calculation.
Especially, when the ILx is large, or V
for V
When I
In this moment, the peak current, ILxmax flowing through the inductor and the driver Tr. is described as
With the formula 4,6, and ILxmax is,
Therefore, peak current is more than I
In the formula 7, peak current ILxmax at discontinuous mode can be calculated. Put Iconst=0 in the formula.
The explanation above is based on the ideal calculation, and the loss caused by Lx switch and external
I
ILxmax
ILxmax
OUT
OUT
=
, Vf (as much as 0.3V) of the diode should be considered.
f
OSC
OUT
=
=
Iconst
×
V
becomes more than formula 5, the current flows through the inductor, then the mode becomes
V
OUT
IN
/V
2
×
+
IN
T
V
×
ON
IN
I
OUT
×
2
/
T
{
+
2
ON
×
V
/L
L
IN
×
×
.................................................................................................................Formula 7
(V
T
ON
OUT
/(2
IN
−
×
V
is low, the loss of V
L)
IN
OUT
)
}
..............................................................................................Formula 8
. Considering the value of ILxmax, the condition of input and output,
+
V
IN
×
Iconst/V
IN
OUT
is generated with the on resistance of the switch. As
...............................................................Formula 6
R1211x
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