Daewoo DTH-14Q1FS Service Manual page 24

Color television
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5) Drive circuit
The STR-S5707 applies the proportional drive system in order to minimize turn-on and satruration loss, and
storage time. In the conventional RCC system, turn-on loss and switching noise due to the surge current
appearing when the power transistor turns on are high as because the transistor is driven by the drive current
shown in Fig. 10-1. In addition, since is decreases linearly when the transistor turn off and a peak value of I
not large, the storage time is long and the V
and the waveforms of the proportional drive system which is applied to the STR-S5707 in order to reduce these
switching loss and shorten the storage time are shown in Fig . 10 and Fig. 10-2 respectively.
Fig .10 D806 and C805 function to reverse-blas between the base and the emitter
VCE
0
Fig .10-1 Waveforms of Conventional
CE(sat)
Drive
OSC
of the transistor during its off state.
IC
V
BE
I
B
Reveres
bias
RCC Power Supply
voltage is high, which results in large turn-off loss. The circuit
R810
C805
D806
VCE
IC
0
I
B
Fig .10-2 Waveforms of power Supply
Using STR-S5707
22
V
BE
Reveres
bias
is
B2

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