MB39A125 Datasheet, PDF (50/64 Pages) Fujitsu Component Limited. – DC/DC Converter IC for Charging Li-ion Battery

MB39A125/126
PC = ID2 × RDS (ON) × Duty
= 3² × 0.018 × 0.672
=: 0.109 W
PS (ON) =
VD × ID × tr × fosc
6
25 × 3 × 15 × 10^−9 × 300 × 10³
=
6
=: 0.056 W
PS (OFF) =
VD × ID (Max) × tf × fosc
6
25 × 3.6 × 42 × 10^−9 × 300 × 10³
=
6
=: 0.189 W
PT = PC + PS (ON) + PS (OFF)
=: 0.109 + 0.056 + 0.189
=: 0.354 W
The above power dissipation figures for the µPA2714GR are satisfied with ample margin at 2.0 W.
12.6 V setting
Input voltage VIN (Max) = 22 V, output voltage VO = 12.6 V, drain current ID = 3 A, oscillation frequency fosc = 300 kHz,
L = 15 µH, drain-source on resistance RDS (ON) =: 18 mΩ, tr=: 15 ns, tf=: 42 ns
Drain current (Max) : ID (Max)
VIN − Vo
ID (Max) = Io +
tON
2L
= 3+
22 − 12.6
2 × 15 × 10^−6
=: 3.6 A
1
×
300 × 10³
× 0.572
Drain current (Min) : ID (Min)
VIN − Vo
ID (Min) = Io −
tON
2L
= 3−
22 − 12.6
2 × 15 × 10^−6
=: 2.4 A
1
×
300 × 10³
× 0.572
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