MB39A214APFT-G-JNERE1 Datasheet, PDF (32/56 Pages) Fujitsu Component Limited. – 2ch DC/DC converter IC with PFM/ PWM synchronous rectification

MB39A214A
2. Selecting parts
Selection of smoothing inductor
The inductor value selects the value that the ripple current peak-to-peak value of the inductor is 50% or less
of the maximum load current as a rough standard. Calculate the inductor value in this case by the following
formula.
L≥
V_IN −V_OUT
¯
V_OUT
LOR¯ I_{OUT_MAX}
V_IN ¯f_OSC
L
I_{OUT_MAX}
LOR
V_IN
V_OUT
f_OSC
: Inductor value [H]
: Maximum load current [A]
: Ripple current peak-to-peak value of inductor/Maximum load current ratio (= 0.5)
: Power supply voltage [V]
: Output setting voltage [V]
: Switching frequency [Hz]
It is necessary to calculate the maximum current value that flows to the inductor to judge whether the
electric current that flows to the inductor is a rated value or less. Calculate the maximum current value of
the inductor by the following formula.
IL_MAX ≥ I_{OUT_MAX} + ^ΔIL
2
IL_MAX : Maximum current value of inductor [A]
I_{OUT_MAX} : Maximum load current [A]
ΔI_L : Ripple current peak-to-peak value of inductor [A]
L
: Inductor value [H]
V_IN
V_OUT
f_OSC
: Power supply voltage [V]
: Output setting voltage [V]
: Switching frequency [Hz]
Inductor current
ILMAX
IOUT_MAX
0
ΔIL
Time
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DS405-00007-1v0-E