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 ∝H,
Drain current (Max) : ID (Max)
ID (Max) = IO + | VIN − VO | ton | |
2L | |||
|
|
= 3 + |
| 19 − 3.3 | |
2 | ⋅ 15 ⋅ 10−6 | ||
|
=: 3.18 (A)
Drain current (Min) : ID (Min)
ID (Min) = IO − | VIN − VO | ton | |
2L | |||
|
|
= 3 − |
| 19 − 3.3 | |
2 | ⋅ 15 ⋅ 10−6 | ||
|
=: 2.82 (A)
⋅ | 1 | ⋅ 0.174 |
500 ⋅ 103 |
⋅ | 1 | ⋅ 0.174 |
500 ⋅ 103 |
25