bd9324efj ROHM Co. Ltd., bd9324efj Datasheet - Page 8

• Manufacturer Part Number: bd9324efj
• Description: Simple Step-down Switching Regulator With Integrated Compensation
• Manufacturer: ROHM Co. Ltd.

(1) Output LC constant (Buck Converter)
Selecting Application Components
The inductance L to use for output is decided by the rated current I
inductance.
Set with sufficient margin because the inductance L value may have the dispersion of ± 30%.
For the capacitor C to use for the output, select the capacitor which has the larger value in the ripple voltage V
value and the drop voltage permissible value at the time of sudden load change.
Perform setting so that the voltage is within the permissible ripple voltage range.
For the drop voltage V
However, 10μsec is the rough calculation value of the DC/DC response speed.
Make Co settings so that these two values will be within the limit values.
IL
Adjust so that I
equation.
Output ripple voltage is decided by the following equation.
∆V
V
PP
∆I
DR
L
=
=
=
OMAX
1
L
DR
Co
∆I
∆I
Fig.
during sudden load change, please perform the rough calculation by the following equation.
L
× R
× (Vcc - Vo) ×
+ ∆I
× 10μsec
ESR +
L
does not reach the rated current value I
I
OMAX
2Co
∆I
reach the rated
value level
L
[V]
+
Vcc
ΔI
Vo
×
L
I
current
OMAX
should not
t
ILR
Vcc
×
Vo
mean
8/13
1
f
×
[A]
1
f
LR
and input current maximum value I
[V]
LR
. At this time, ∆I
VCC
I
L
L
Fig.
L
Co
can be obtained by the following
Vo
OMAX
PP
of the
permissible