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Discussion Groups | Piclist | Vcc issues.
A discussion group for the PICMicro microcontroller. Also called the Microchip PIC, this list is dedicated to the use and abuse of this fine, simple, microcontroller. Close to topic posts are welcome, ie. general electronics.
Vcc issues. - Ronald Delap - May 29 22:20:42 2009
Good morning all - I am new to the group and have a dilemma which
perhaps will be a new one for you.
I am designing a solar cell battery charger that uses a pic 675. The
issue I have is that the solar cells will put out anywhere from 2-12
volts, depending on sunlight conditions. This voltage must be used to
obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
cell voltage out. I have designed circuits in the past for other
applications, to step up a low voltage (e.g. 2-4 volts stepped up to
5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
The conundrum with this design is that either situation can occur, and
the circuits I've designed in the past are for one or the other
situation, but not both. My step up designs choke when the input
voltage exceeds the desired output voltage, and my step-down designs
don't work if the input is less than the desired output.
It is imperative that the final design be very efficient, so zener
clamps are not desireable as they "waste" available current coming from
the solar cells.
Any thoughts?
Thanks,
Ron DeLap
------------------------------------
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perhaps will be a new one for you.
I am designing a solar cell battery charger that uses a pic 675. The
issue I have is that the solar cells will put out anywhere from 2-12
volts, depending on sunlight conditions. This voltage must be used to
obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
cell voltage out. I have designed circuits in the past for other
applications, to step up a low voltage (e.g. 2-4 volts stepped up to
5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
The conundrum with this design is that either situation can occur, and
the circuits I've designed in the past are for one or the other
situation, but not both. My step up designs choke when the input
voltage exceeds the desired output voltage, and my step-down designs
don't work if the input is less than the desired output.
It is imperative that the final design be very efficient, so zener
clamps are not desireable as they "waste" available current coming from
the solar cells.
Any thoughts?
Thanks,
Ron DeLap
------------------------------------
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
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Re: Vcc issues. - demolitron - May 30 4:14:45 2009
This may be overkill, but a SEPIC (Single Ended Primary Inductor Converter) sounds like
the ticket for you. Caution, the SEPIC converter is a little complicated regarding
stabilizing the feedback loops.
Here is a link to an App Note that is VERY helpful
http://www.maxim-ic.com/appnotes.cfm/an_pk/1051/
If you don't like the SEPIC route, take a look at this Buck-Boost switcher that uses a MCU to control it...
http://www.st.com/stonline/products/literature/anp/12476.pdf
--- In p...@yahoogroups.com, Ronald Delap wrote:
>
> Good morning all - I am new to the group and have a dilemma which
> perhaps will be a new one for you.
>
> I am designing a solar cell battery charger that uses a pic 675. The
> issue I have is that the solar cells will put out anywhere from 2-12
> volts, depending on sunlight conditions. This voltage must be used to
> obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
> cell voltage out. I have designed circuits in the past for other
> applications, to step up a low voltage (e.g. 2-4 volts stepped up to
> 5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
> The conundrum with this design is that either situation can occur, and
> the circuits I've designed in the past are for one or the other
> situation, but not both. My step up designs choke when the input
> voltage exceeds the desired output voltage, and my step-down designs
> don't work if the input is less than the desired output.
>
> It is imperative that the final design be very efficient, so zener
> clamps are not desireable as they "waste" available current coming from
> the solar cells.
>
> Any thoughts?
>
> Thanks,
> Ron DeLap
>
------------------------------------
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
Here is a link to an App Note that is VERY helpful
http://www.maxim-ic.com/appnotes.cfm/an_pk/1051/
If you don't like the SEPIC route, take a look at this Buck-Boost switcher that uses a MCU to control it...
http://www.st.com/stonline/products/literature/anp/12476.pdf
--- In p...@yahoogroups.com, Ronald Delap
>
> Good morning all - I am new to the group and have a dilemma which
> perhaps will be a new one for you.
>
> I am designing a solar cell battery charger that uses a pic 675. The
> issue I have is that the solar cells will put out anywhere from 2-12
> volts, depending on sunlight conditions. This voltage must be used to
> obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
> cell voltage out. I have designed circuits in the past for other
> applications, to step up a low voltage (e.g. 2-4 volts stepped up to
> 5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
> The conundrum with this design is that either situation can occur, and
> the circuits I've designed in the past are for one or the other
> situation, but not both. My step up designs choke when the input
> voltage exceeds the desired output voltage, and my step-down designs
> don't work if the input is less than the desired output.
>
> It is imperative that the final design be very efficient, so zener
> clamps are not desireable as they "waste" available current coming from
> the solar cells.
>
> Any thoughts?
>
> Thanks,
> Ron DeLap
>
------------------------------------
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Re: Vcc issues. - jwoo...@activation.net - May 30 8:56:39 2009
It depends on your sunlight situation but you could try dealing with one
of the two states and then using a battery for the other state. As long as
one of the states happens every day you can charge the battery during that
state and go dormant in the other state.
What is the actual physical problem you are trying to solve?
ttyl
John
------------------------------------
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of the two states and then using a battery for the other state. As long as
one of the states happens every day you can charge the battery during that
state and go dormant in the other state.
What is the actual physical problem you are trying to solve?
ttyl
John
------------------------------------
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Re: Vcc issues. - d70mike - May 30 8:56:43 2009
if i may ask why 2 volts
can not do a lot with that?
but i think even a dc-dc will not work
how about a rechargeable startup powersupply to get it past the 2 volt panel voltage can be charged off load only there to start up
otherwise whait for enough sunlight to get the 5 volts
or use a panel just for the pic
a good panel will put out more like 17 volts no load most cheap panels only put out 12 volts as they are designed to run with no regulator.used to be in the solar bus.
--- In p...@yahoogroups.com, Ronald Delap wrote:
>
> Good morning all - I am new to the group and have a dilemma which
> perhaps will be a new one for you.
>
> I am designing a solar cell battery charger that uses a pic 675. The
> issue I have is that the solar cells will put out anywhere from 2-12
> volts, depending on sunlight conditions. This voltage must be used to
> obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
> cell voltage out. I have designed circuits in the past for other
> applications, to step up a low voltage (e.g. 2-4 volts stepped up to
> 5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
> The conundrum with this design is that either situation can occur, and
> the circuits I've designed in the past are for one or the other
> situation, but not both. My step up designs choke when the input
> voltage exceeds the desired output voltage, and my step-down designs
> don't work if the input is less than the desired output.
>
> It is imperative that the final design be very efficient, so zener
> clamps are not desireable as they "waste" available current coming from
> the solar cells.
>
> Any thoughts?
>
> Thanks,
> Ron DeLap
>
------------------------------------
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
can not do a lot with that?
but i think even a dc-dc will not work
how about a rechargeable startup powersupply to get it past the 2 volt panel voltage can be charged off load only there to start up
otherwise whait for enough sunlight to get the 5 volts
or use a panel just for the pic
a good panel will put out more like 17 volts no load most cheap panels only put out 12 volts as they are designed to run with no regulator.used to be in the solar bus.
--- In p...@yahoogroups.com, Ronald Delap
>
> Good morning all - I am new to the group and have a dilemma which
> perhaps will be a new one for you.
>
> I am designing a solar cell battery charger that uses a pic 675. The
> issue I have is that the solar cells will put out anywhere from 2-12
> volts, depending on sunlight conditions. This voltage must be used to
> obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
> cell voltage out. I have designed circuits in the past for other
> applications, to step up a low voltage (e.g. 2-4 volts stepped up to
> 5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
> The conundrum with this design is that either situation can occur, and
> the circuits I've designed in the past are for one or the other
> situation, but not both. My step up designs choke when the input
> voltage exceeds the desired output voltage, and my step-down designs
> don't work if the input is less than the desired output.
>
> It is imperative that the final design be very efficient, so zener
> clamps are not desireable as they "waste" available current coming from
> the solar cells.
>
> Any thoughts?
>
> Thanks,
> Ron DeLap
>
------------------------------------
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
Re: Re: Vcc issues. - Daryl Berryhill - May 30 10:45:31 2009
use a MAX710 is a buck boost controller needs 5 componets. it will
boost all the down to .8v to deliver 5V / 3V at up to 1.5A. it also
has a buck mode that will step down voltage from a max of 16v to 5V / 3V
Maxim also makes a MAX711 model. same function but adjustable
voltages with addition of 2 extra resisters
they also have a very nice eval kit for $50 that is well worth it.
Max710 / Max711 overview
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1742/t/al
Max710 / Max711 datasheet
http://datasheets.maxim-ic.com/en/ds/MAX710-MAX711.pdf
> > Good morning all - I am new to the group and have a dilemma which
> > perhaps will be a new one for you.
> >
> > I am designing a solar cell battery charger that uses a pic 675. The
> > issue I have is that the solar cells will put out anywhere from 2-12
> > volts, depending on sunlight conditions. This voltage must be used to
> > obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
> > cell voltage out. I have designed circuits in the past for other
> > applications, to step up a low voltage (e.g. 2-4 volts stepped up to
> > 5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
> > The conundrum with this design is that either situation can occur, and
> > the circuits I've designed in the past are for one or the other
> > situation, but not both. My step up designs choke when the input
> > voltage exceeds the desired output voltage, and my step-down designs
> > don't work if the input is less than the desired output.
> >
> > It is imperative that the final design be very efficient, so zener
> > clamps are not desireable as they "waste" available current coming from
> > the solar cells.
> >
> > Any thoughts?
> >
> > Thanks,
> > Ron DeLap
> >
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
boost all the down to .8v to deliver 5V / 3V at up to 1.5A. it also
has a buck mode that will step down voltage from a max of 16v to 5V / 3V
Maxim also makes a MAX711 model. same function but adjustable
voltages with addition of 2 extra resisters
they also have a very nice eval kit for $50 that is well worth it.
Max710 / Max711 overview
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1742/t/al
Max710 / Max711 datasheet
http://datasheets.maxim-ic.com/en/ds/MAX710-MAX711.pdf
> > Good morning all - I am new to the group and have a dilemma which
> > perhaps will be a new one for you.
> >
> > I am designing a solar cell battery charger that uses a pic 675. The
> > issue I have is that the solar cells will put out anywhere from 2-12
> > volts, depending on sunlight conditions. This voltage must be used to
> > obtain a somewhat stable Vcc for the Pic chip, regardless of the solar
> > cell voltage out. I have designed circuits in the past for other
> > applications, to step up a low voltage (e.g. 2-4 volts stepped up to
> > 5), or to step down a high voltage (e.g. 10 volts stepped down to 5).
> > The conundrum with this design is that either situation can occur, and
> > the circuits I've designed in the past are for one or the other
> > situation, but not both. My step up designs choke when the input
> > voltage exceeds the desired output voltage, and my step-down designs
> > don't work if the input is less than the desired output.
> >
> > It is imperative that the final design be very efficient, so zener
> > clamps are not desireable as they "waste" available current coming from
> > the solar cells.
> >
> > Any thoughts?
> >
> > Thanks,
> > Ron DeLap
> >
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