MB39A112 Datasheet, PDF (22/35 Pages) Fujitsu Component Limited. – 3-ch DC/DC Converter IC

MB39A112
PC = ID2 × RDS (ON) × Duty
= 1.5² × 0.18 × 0.1
=: 0.04 W
PS (ON) = ^{VD × ID × tr × fosc}
6
12 × 1.5 × 2.9 × 10^−9 × 2350 × 10³
=
6
=: 0.02 W
PS (OFF) =
VD × ID (Max) × tf × fosc
6
12 × 1.61 × 8.7 × 10^−9 × 2350 × 10³
=
6
=: 0.066 W
PT = Pc + PS (ON) + PS (OFF)
=: 0.04 + 0.02 + 0.066
=: 0.126 W
The above power dissipation figures for the MCH3312 are satisfied with ample margin at 1.0 W (Ta = +25 °C) .
• CH2
Input voltage VIN = 12 V, output voltage VO = 3.3 V, drain current ID = 1.0 A, oscillation frequency fOSC = 2350 kHz,
L = 3.3 µH, drain-source on resistance RDS(ON) =: 180 mΩ, tr =: 2.9 ns, tf =: 8.7 ns.
Drain current (Max) : ID (Max)
ID (Max) = Io +
VIN − Vo
tON
2L
= 1+
12 − 3.3
2 × 3.3 × 10^−6
=: 1.15 A
1
× _{2350 × 103} × 0.275
Drain current (Min) : ID (Min)
ID (Min) = Io −
VIN − Vo
tON
2L
= 1−
12 − 3.3
2 × 3.3 × 10 ^−6
=: 0.85 A
1
× _{2350 × 103} × 0.275
PC = ID2 × RDS (ON) × Duty
= 1² × 0.18 × 0.275
=: 0.0495 W
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