Propeller Supply Voltage (Vcc or Vdd)
Bruce Bates
Posts: 3,045
Propeller Gurus -
Based on previous testing done, which was posted on this forum by Dr. Tracy Allen (thanks Tracy!), it appears that brownout on the Propeller occurs at or near 2.7 volts. It also appears from various postings that the Propeller is expected to run at 3.3 volts (Vcc, Vdd or call it what you will). I'm just wondering what the Vcc/Vdd (max) is, and I hope it's not 3.3 volts.
The reason for the question is as follows. The "sequence" (if you will) for single and multiple rechargable (NiCD, NiMH and other) batteries (Vmax) is generally accepted to be: 1.25, 2.50, 3.75 VDC. It appears there is a possibility that the Propeller may miss these limits, and thus more circuity will be required, unless the maximum permissible voltage is in excess of 3.3 volts, or the minimum can be lowered to 2.5 volts?
Regards,
Bruce Bates
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Based on previous testing done, which was posted on this forum by Dr. Tracy Allen (thanks Tracy!), it appears that brownout on the Propeller occurs at or near 2.7 volts. It also appears from various postings that the Propeller is expected to run at 3.3 volts (Vcc, Vdd or call it what you will). I'm just wondering what the Vcc/Vdd (max) is, and I hope it's not 3.3 volts.
The reason for the question is as follows. The "sequence" (if you will) for single and multiple rechargable (NiCD, NiMH and other) batteries (Vmax) is generally accepted to be: 1.25, 2.50, 3.75 VDC. It appears there is a possibility that the Propeller may miss these limits, and thus more circuity will be required, unless the maximum permissible voltage is in excess of 3.3 volts, or the minimum can be lowered to 2.5 volts?
Regards,
Bruce Bates
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Comments
Playing with 'maximum' voltages is just a fancy way of killing ships faster.
(MTBF tends to take a nosedive )
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Don't visit my new website...
Should be Vdd...
I was in Chips' office in February and he was running a Propeller at 5V at 80MHz without any obvious problems. I would think that 3.75V should be fine.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
With four cells you are just generating heat from extra batteries and wasting your money.
These seem to have an auto-shut off at about 2volts, which is optimal for preserving the life of 3.7V lithium polymer cells among others.
You really don't want to run the NiCads or the Lithium Polymer all the way down. They suffer damage to their chemistry.
Of course if you just want to use alkaline, no regulator is just fine. And you would be optimally using only two [noparse][[/noparse]maybe three, but probably just to provide a battery case that can switch easily between NiCads, NiMH, and Alkaline].
So, it seems to me that battery integration is much easier at 3.3volts with newer regulators than at 5.0volts with the 7805.
And for those of use that want to use AA cells, one less battery is called for.
Of course with such a wide range regulator and a big heat sink, you can just plug it into nearly any handy DC source.
Lots of good choices if you stay lower.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan