5
Motorola TMOS Power MOSFET Transistor Device Data
DRAIN–TO–SOURCE DIODE CHARACTERISTICS
0.5
0.6
0.7
0.8
0.95
0
5
15
25
35
VSD, SOURCE–TO–DRAIN VOLTAGE (VOLTS)
Figure 8. Gate–To–Source and Drain–To–Source
Voltage versus Total Charge
I
Figure 9. Resistive Switching Time
Variation versus Gate Resistance
RG, GATE RESISTANCE (OHMS)
0
10
100
1000
100
10
t
VDD = 75 V
ID = 35 A
VGS = 10 V
TJ = 25
°
C
tr
tf
td(off)
td(on)
VGS = 0 V
TJ = 25
°
C
Figure 10. Diode Forward Voltage versus Current
120
V
100
60
40
20
0
0
8.0
4.0
0
QT, TOTAL CHARGE (nC)
V
12
6.0
2.0
20
80
100
VGS
40
0.55
0.65
0.75
0.85
10
20
30
VDS
Q2
Q1
Q3
60
10
80
QT
TJ = 25
°
C
ID = 35 A
0.9
SAFE OPERATING AREA
The Forward Biased Safe Operating Area curves define
the maximum simultaneous drain–to–source voltage and
drain current that a transistor can handle safely when it is for-
ward biased. Curves are based upon maximum peak junc-
tion temperature and a case temperature (TC) of 25
°
C. Peak
repetitive pulsed power limits are determined by using the
thermal response data in conjunction with the procedures
discussed in AN569, “Transient Thermal Resistance–General
Data and Its Use.”
Switching between the off–state and the on–state may tra-
verse any load line provided neither rated peak current (IDM)
nor rated voltage (VDSS) is exceeded and the transition time
(tr,tf) do not exceed 10
μ
s. In addition the total power aver-
aged over a complete switching cycle must not exceed
(TJ(MAX) – TC)/(R
θ
JC).
A Power MOSFET designated E–FET can be safely used
in switching circuits with unclamped inductive loads. For reli-
able operation, the stored energy from circuit inductance dis-
sipated in the transistor while in avalanche must be less than
the rated limit and adjusted for operating conditions differing
from those specified. Although industry practice is to rate in
terms of energy, avalanche energy capability is not a con-
stant. The energy rating decreases non–linearly with an in-
crease of peak current in avalanche and peak junction
temperature.
Although many E–FETs can withstand the stress of drain–
to–source avalanche at currents up to rated pulsed current
(IDM), the energy rating is specified at rated continuous cur-
rent (ID), in accordance with industry custom. The energy rat-
ing must be derated for temperature as shown in the
accompanying graph (Figure 12). Maximum energy at cur-
rents below rated continuous ID can safely be assumed to
equal the values indicated.