Timeline for Oops! N-channel Mosfet on sinking output
Current License: CC BY-SA 3.0
17 events
| when toggle format | what | by | license | comment | |
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| Apr 28, 2016 at 14:35 | history | edited | JoeChiphead | CC BY-SA 3.0 |
Proposed pullup arrangement
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| Apr 21, 2016 at 20:16 | answer | added | Master | timeline score: 0 | |
| Apr 21, 2016 at 20:08 | comment | added | Master | I suggest using PNP BJT of normal switching type. See the schematics in the answer. | |
| Apr 21, 2016 at 13:07 | comment | added | JoeChiphead | @Master Any thoughts? | |
| Apr 20, 2016 at 22:27 | comment | added | JoeChiphead | @Master1, Thanks. Since this is a prototype, I was thinking to do just that (using two outputs) just to prove my circuits works. In final design, which must use the '6964, what might I use for FET, resistor configuration to allow use of separate VAA supply for LEDs and one output per LED? All configurations I've seen on this site need a resistor pullup for P-channel mosfet. (See other other comments regarding why separate VAA) Thanks! | |
| Apr 20, 2016 at 21:54 | comment | added | Master | In case you really switch on only one LED at a time - you can use one resistor. Although this puts an artificial limitation on your design. | |
| Apr 20, 2016 at 21:52 | comment | added | Master | Then I suggest: removing MOSFETs, using 2 outputs of MAX6964 in parallel for each LED. You can safely drive about 80-90 mA in each LED by this design. Of course, you need spare outputs. | |
| Apr 20, 2016 at 21:31 | comment | added | JoeChiphead | @Master1, 1 LED per output and can draw up to 100mA ea. A working circuit that I started with was a 74HC4514 driving the base of the N-Channel mosfet. Why would I now need separate resistor per LED? Note, that both LED will never be turned on at the same time. | |
| Apr 20, 2016 at 19:53 | answer | added | Ignacio Vazquez-Abrams | timeline score: 1 | |
| Apr 20, 2016 at 19:44 | history | edited | JoeChiphead | CC BY-SA 3.0 |
Ommited important detail regarding VAA
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| Apr 20, 2016 at 19:39 | comment | added | Master | And, by the way, you have to use separate "R6" resistors: one resistor for each LED. | |
| Apr 20, 2016 at 19:38 | comment | added | Master | What LEDs (part number) do you use in your design? How many LEDs do you want to connect to one output? | |
| Apr 20, 2016 at 19:36 | answer | added | Steve G | timeline score: 2 | |
| Apr 20, 2016 at 19:30 | answer | added | Jonas Schäfer | timeline score: 3 | |
| Apr 20, 2016 at 19:29 | history | edited | JoeChiphead | CC BY-SA 3.0 |
added 9 characters in body
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| Apr 20, 2016 at 19:26 | comment | added | Ignacio Vazquez-Abrams | Why not just connect the gate pad to the drain pad and omit the MOSFET entirely? | |
| Apr 20, 2016 at 19:11 | history | asked | JoeChiphead | CC BY-SA 3.0 |