APPLICATION DATA (Cont’d)
Fig. F : TURN-OFF CHARACTERISTICS.
V
IL
TRANSISTOR
I
t
STTA312B
Turn-on losses :
(in the transistor, due to the diode)
P5 = VR
×
IRM 2 × (3+2 × S) F
6 x dIF ⁄ dt
+
VR
×
IRM × IL ×(S +
2 × dIF ⁄ dt
2)
×
F
I
dI F /dt
DIODE
V
ta tb
t
I RM
dIR /dt
VR
trr = ta + tb S = tb / ta
I
dIF /dt = VR /L
RECTIFIER
OPERATION
V
ta tb
IRM
dI R /dt
t
VR
trr = ta + tb
S = tb/ta
Fig. G : TURN-ON CHARACTERISTICS.
IF
dIF /dt
I Fmax
0
t
VF
V Fp
1.1V F
0
VF
tfr
t
Turn-off losses :
P3 = VR
× IRM 2 × × S × F
6 x dIF ⁄ dt
Turn-off losses :
with non negligible serial inductance
P3’ = VR
× IRM 2 × S
6 x dIF ⁄ dt
×
F+L
×
IRM 2 ×
2
F
P3, P3’ and P5 are suitable for power MOSFET
and IGBT
Turn-on losses :
P4 = 0.4 (VFP - VF) x IFmax x tfr x F
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