APPLICATION NOTE
AN-3002
and output transistors are turned on causing the “Output” to a
logic “0” state. The 4.7 M
Ω
resistor will now tend to reduce
the output transistor’s turn-off time.
If you have not looked over the 6N139 specification sheet,
you may not be totally aware of the current capabilities of
Fairchild Semiconductor optocouplers.
(5V)
+V
6N139
4.7KΩ
4.7KΩ
4.7KΩ
4.7K
OUTPUT TO TTL
4.7KΩ
*Normally OPEN momentary push-button
or
TTL output with open collector
GROUND
FOR RESET*
Figure 7. Latching Output Circuit for 6N139
(5V)
+V
6N139
4.7KΩ
4.7MΩ
OUTPUT TO TTL
Figure 8. NON-Latching Output Circuit for 6N139
REV. 4.00 4/30/02
3
FAIRCHILD [ FAIRCHILD SEMICONDUCTOR ]
