BU808DFX STMicroelectronics, BU808DFX Datasheet - Page 4

• Manufacturer Part Number: BU808DFX
• Description: HIGH VOLTAGE FAST-SWITCHING NPN POWER DARLINGTON TRANSISTOR
• Manufacturer: STMicroelectronics

BU808DFX
Switching Time Inductive Load at 16KHZ
BASE DRIVE INFORMATION
In order to saturate the power switch and reduce
conduction losses, adequate direct base current
I
100
negative base current I
turn off the power transistor (retrace phase).
Most of the dissipation, in the deflection
application, occurs at switch-off. Therefore it is
essential to determine the value of I
minimizes power losses, fall time t
consequently, T
defined to give total power losses, t
function of I
frequencies for choosing the optimum negative
4/7
B1
has to be provided for the lowest gain h
o
C (line scan phase). On the other hand,
B2
j
. A new set of curves have been
at both 16 KHz scanning
B2
must be provided to
s
and t
B2
f
f
which
FE
as a
and,
at
drive. The test circuit is illustrated in figure 1.
Inductance L
negative base current I
excess carrier in the collector when base current
is still present, this would avoid any tailing
phenomenon in the collector current.
The values of L and C are calculated from the
following equations:
Where I
flyback voltage, f= frequency of oscillation during
retrace.
Reverse Biased SOA
1
2
L I
C
2
C
= operating collector current, V
1
2
C V
1
serves to control the slope of the
CEfly
2
B2
to recombine the
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2 f
L
1
C
CEfly
=