tn8d51a ON Semiconductor, tn8d51a Datasheet - Page 9

• Manufacturer Part Number: tn8d51a
• Description: Separately-excited Step-down Switching Regulator 12v Output Type
• Manufacturer: ON Semiconductor

Example of Over-voltage Protection Circuit.
Generally, in constant-voltage power supply circuit, output voltage will become higher than the specified value (over-
voltage state) in case of any failures or PC board solderability defects. To minimize the damage caused by this over
voltage, we recommend setting an over-voltage protection circuit.
Example of Over-voltage Protection Circuit
The thyristor will operate when it accept an over-voltage (V OUT ) signal, then the fuse is melted and the input power is cut
off, then the operation of IC1 is stopped.
In designing, the following confirmations are necessary in actual circuit.
1) How the over-voltage protection circuit operates and its effects.
2) Is there any malfunction due to ambient temperature change of each device or exogenous noises?
GND
V IN
FUSE
F1
GND
V IN
+
FUSE
F1
THYRISTOR
THYRISTOR
Over-voltage Protection Circuit Example
C
C
1
R
2 3 4
R
Constant-voltage
IC1
TN8D51A
power supply
5
ZD
V OUT
GND
ZD
IT12639
+
Continued on next page.
V OUT
GND
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