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MWS
Joined: 22 Aug 2009
Posts: 2262
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 Posted: Tue Jan 25, 2022 5:46 pm Post subject: |
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| sentinel wrote: | | My apologies |
Let me say: my apologies, as I did not understand your intention.
| Quote: | | We may have been talking at cross purposes. |
Yes, sort of.
Not sure how far your simulation went, but as you saw I tried to include also the supercap.
If the supercap is completely empty, charging burdens R5 in your schema, R1 in mine that far, that the voltage at tp1 doesn't come up, with the effect, that the M168 does not get out of sleep.
As soon it's charged, everything looks ok. |
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sentinel
Joined: 02 Feb 2009
Posts: 141
Location: Tasmania
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| Posted: Wed Jan 26, 2022 4:09 pm Post subject: |
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The supply is half wave 24 VAC so can supply the voltage and current to lift the output even when the maximum supercap charging current of 33 mA is being drawn at power up.
I've changed a couple of values to try to improve the performance. I had to use the LM317 in the simulator as there is no 3.3 V device in the library.
The Power_on sense voltage (green trace in the graph) rises to the input high threshold (~1.75 V) 6 seconds after power on. Vbat reaches the 1.8 V BOD level after 105 mS and the supercap reaches that level after 17 seconds.
I'm happy with that behaviour.
Thanks to everyone for all the suggestions and exchange of ideas. |
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MWS
Joined: 22 Aug 2009
Posts: 2262
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| Posted: Wed Jan 26, 2022 7:56 pm Post subject: |
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| sentinel wrote: | | Thanks to everyone for all the suggestions and exchange of ideas. |
You want to duck out just as we succeed over-engeneering it?  |
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sentinel
Joined: 02 Feb 2009
Posts: 141
Location: Tasmania
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| Posted: Wed Jan 26, 2022 11:58 pm Post subject: |
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Haha. Much as I've enjoyed the back-and-forth of this particular tennis match, it's time to go and make and test the thing.
Besides, I'm terrified that you might find yet another flaw in the circuit  |
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