| ??? 02/08/05 11:54 Read: times |
#86887 - PC817 Responding to: ???'s previous message |
Raghu:
I have used similar opto couplers in projects. First note that the 817 coupler data sheet (http://www.isocom.com/datasheets/db92275.pdf) specifies a typical rise time of signal at 4us but a maximum time more on the order of 18us with a 100 ohm load. I have found by trial and error that sometimes the speed can be increased by lowering the load resistor. It is also possible to see some increase in performance by connecting the output collector to +5V and inserting the load resistor between the emitter and GND. At the specified test load of 2mA into a 100 ohm load the net voltage range across the 100 ohm resistor is 0.2 volts. This is hard to work with via direct interface to logic so I can see why you try 1K instead. But try the emitter follower connection. You may be surprised. Michael Karas |
| Topic | Author | Date |
| PC817 optocoupler design aspects | 01/01/70 00:00 | |
| For AC i use the PC814 | 01/01/70 00:00 | |
| not this way | 01/01/70 00:00 | |
| PC817 | 01/01/70 00:00 | |
| assorted comments | 01/01/70 00:00 | |
| Optocoupler | 01/01/70 00:00 | |
| Opto Coupler Design Guide | 01/01/70 00:00 | |
So far so good.. | 01/01/70 00:00 |