MB39A104_08 Datasheet, PDF (25/40 Pages) Fujitsu Component Limited. – 2-ch DC/DC Converter IC with Overcurrent Protection

MB39A104
PC = ID ² × RDS (ON) × Duty
= 3 ² × 0.05 × 0.263
=: 0.118 W
PS (ON)
=
VD (Max)
× ID × tr × fOSC
6
=
19 × 3 × 100 × 10^−9 × 500 × 10³
6
=: 0.475 W
PS (OFF)
=
VD (Max) × ID (Max) × tf × fOSC
6
=
19 × 3.25 × 100 × 10^−9 × 500 × 10³
6
=: 0.515 W
PT = PC + PS (ON) + PS (OFF)
=: 0.118 + 0.475 + 0.515
=: 1.108 W
The above power dissipation figures for the TPC8102 are satisfied with ample margin at 2.4 W (Ta = +25 °C) .
CH2
Input voltage VIN (Max) = 19 V output voltage VO = 3.3 V, drain current ID = 3 A, Oscillation frequency
fOSC = 500 kHz, L = 15 µH, drain-source on resistance RDS (ON) =: 50 mΩ, tr = tf =: 100 ns.
Drain current (Max) : ID (Max)
ID (Max)
= IO +
VIN − VO
2L
ton
=3+
19 − 3.3
2 × 15 × 10^−6
×
1
500 × 10³
× 0.174
=: 3.18 (A)
Drain current (Min) : ID (Min)
ID (Min)
= IO −
VIN − VO
2L
ton
=3−
19 − 3.3
2 × 15 × 10^−6
×
1
500 × 10³
× 0.174
=: 2.82 (A)
25