BUH1015HI Datasheet, PDF (4/7 Pages) STMicroelectronics – HIGH VOLTAGE FAST-SWITCHING NPN POWER TRANSISTOR

BUH1015HI
Power Losses at 64 KHz
Switching Time Inductive Load at 64KHz
(see figure 2)
Reverse Biased SOA
BASE DRIVE INFORMATION
In order to saturate the power switch and reduce
conduction losses, adequate direct base current
IB1 has to be provided for the lowest gain hFE at
Tj = 100 ^oC (line scan phase). On the other hand,
negative base current IB2 must be provided the
transistor to turn off (retrace phase). Most of the
dissipation, especially in the deflection
application, occurs at switch-off so it is essential
to determine the value of IB2 which minimizes
power losses, fall time tf and, consequently, Tj. A
new set of curves have been defined to give total
power losses, ts and tf as a function of IB1 at 64
KHz scanning frequencies for choosing the
optimum drive. The test circuit is illustrated in
figure 1.
The values of L and C are calculated from the
following equations:
1
2
L
(I_C)²
=
1
2
C
(V_CEfly)²
ω
=
2
πf
=
1
√LC
Where IC= operating collector current, VCEfly=
flyback voltage, f= frequency of oscillation during
retrace.
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