Timeline for Oops! N-channel Mosfet on sinking output
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 28, 2016 at 14:36 | comment | added | JoeChiphead | See new image edited into original post above labeled [EDIT 2016-04-20 proposed:] | |
| Apr 28, 2016 at 14:29 | comment | added | JoeChiphead | Thanks. I understand. What if the pullup tied to the +3.3V and not to VAA? MAX6964 can sink 50mA. I've drawn it, but Forum comment doesn't seem to allow pasting new image... | |
| Apr 26, 2016 at 12:10 | comment | added | Master | Sorry for a late reply. Yes, you can, however, the problem is: varying current from VAA definitely changes the voltage at VAA node. This makes a current through R1 uncertain. If VAA is a true current source with high output impedance: I suggest reduction of R2 to few Ohms (may be, no R2 at all). Then VAA voltage is almost direct voltage drop over the LED D2. It depends on VAA current a little. Then VAA is 1.8 - 3.2 depending on the LED type. You can set R1 according to the minimal voltage, for example, to 330 Ohms. | |
| Apr 22, 2016 at 18:34 | comment | added | JoeChiphead | this is excellent. Could I still use this circuit if VAA was an externally controlled current source varying between ~=5ma to 100ma ( V ~=1.5V to 1.9V)? | |
| Apr 21, 2016 at 20:16 | history | answered | Master | CC BY-SA 3.0 |