BD8166EFV-E2 查看數據表（PDF） - ROHM Semiconductor
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BD8166EFV-E2 Datasheet PDF : 21 Pages
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BD8166EFV
Technical Note
●Selecting Application Components
(1) Output LC constant
The inductance L to use for output is decided by the rated current ILR and input current maximum value IOMAX of the
inductance.
Vin
IL
IL + IL/2 should not reach
M1 ON
M1 OFF
the rated value level
II
M1
ILR
IL
Vo
ΔIL
ton
T
IL
L
D2
M2
D1
M0
Co
t
Fig. 28
Fig.29
Adjust so that IL+ΔIL/2 does not reach the rated current value ILR. At this time, IL and ∆IL can be obtained by the
following equation.
IL=
(1
+
Vo
Vin
) Io×
1
η
[A]
(η:efficiency)
ΔIL=
1
L
{Vin×Vo / (Vin + Vo)} ×
1
f
[A]
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 VPP
permissible value and the drop voltage permissible value at the time of sudden load change.
Output ripple voltage is decided by the following equation.
ΔVPP =
―
(IL
ΔIL
2
)RESR +
Io
Co
( Vin / (Vin + Vo)) ×
1
f
Perform setting so that the voltage is within the permissible ripple voltage range.
For the drop voltage VDR during sudden load change, please perform the rough calculation by the following equation.
VDR =
ΔI
Co
× 10µ sec
[V]
However, 10 µs 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.
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9/17
2015.12 - Rev.C
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