Secondary Rectification & Smoothing Circuit; Detection Circuit; S6V, +15.5V Overvoltage Protection Circuit - Toshiba TLP411E Technical Training Manual

2-7. Secondary Rectification & Smoothing
Circuit
High-voltage applied to N
P
ously, pulse by means of the switching operation and then
converted to low voltage at both ends of the secondary
side winding N via T001 and is output after rectifica-
S
tion/smoothing.
B
A
T001
+6V
N
S
N
P
I
Fig. 1-9
2-8. +6V Detection Circuit
+6V voltage is divided by VR101, R113 and R114, it is
input to the gate of IC101 and then it is compared with
the reference voltage of that IC. This potential difference
flows into PC002 as current variation which is then
transferred to the primary side control circuit to control
output voltage.
L101
PC002
K
G
A
IC101
Fig. 1-10
becomes, as mentioned previ-
Q001
V
DS
A
I
0
+6V
B
0
+S6V
VR101
R113
R114
G
2-9. +6V, +S6V, +15.5V Overvoltage
Protection Circuit
As shown in Fig. 1-9, the overvoltage of +6V and +S6V
is detected by ZD101 and the overvoltage +15.5V is de-
tected by ZD401.
When the overvoltage is detected, current flows to zener
diode, the current then flows to PC001. This is transferred
to the primary control circuit and trigger signal is given
to the gate of thyristor SCR002 to short-circuit the gate of
Q001. As a result, Q001 turns off and the oscillation stops.
The circuit is put to the latch mode. Therefore, no activa-
tion is possible even overvoltage state is released. Activa-
tion is made possible by reentry of input.
ZD101
D102
R102
PC001
1-5
+S6V
+6V
+15.5V
ZD401
R103
Fig. 1-11