>
> Hello,
>
> has anyone a LOW COST / LOW CURRENT idea that could help solving the
> following alimentation problem?
>
> A 16C505 or 12C508 shall be used as an ecoder for a 12V battery powered 3
> button handheld transmitter. Because of the needed code completion feature
> after button release, the power must be present permanently / resp. as long
> as the PIC needs it.
>
> The two approaches i see are:
>
> a) use a very low power 5V regulator which is comparable expensive.  That
> way the PIC could wakeup from sleep at button activation for as long time as
> needed to complete a message after release of the button.
>
> b) use a low cost 7805 regulator or a zener which draws to much current to
> be allways on. Thus, the buttons need to switch the power directly and the
> PIC needs to hold the power in the ON-state via some transistors. After
> completion it could cut itself and also the stabilizing circuit from power
> by releasing the transistors.
>
> Is there a third possibility i dont think of?  I feel that from the two
> mentioned either has its drawbacks in a low cost radio control? What would
> the gurus advice?
>
> Germain Morbe
>
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> This may not fit into your design, but there are low power switching
> regulators which require fewer components than a typical switching design,
> and feature shut-down modes which reduce current draw to the uA range.  A
> button could supply enough power to the shutdown to start it up, and the
> uC could shut it down as long as the button is not pressed.
>
> You might try this one, for instance...
> http://dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=1155&Fam=DCDC_All&TREE=PowerSupplies.asp&HP=PowerSupplies.cfm
>
> -Adam
>
> Germain Morbe wrote:
> >
> > Hello,
> >
> > has anyone a LOW COST / LOW CURRENT idea that could help solving the
> > following alimentation problem?
> >
> > A 16C505 or 12C508 shall be used as an ecoder for a 12V battery powered 3
> > button handheld transmitter. Because of the needed code completion feature
> > after button release, the power must be present permanently / resp. as long
> > as the PIC needs it.
> >
> > The two approaches i see are:
> >
> > a) use a very low power 5V regulator which is comparable expensive.  That
> > way the PIC could wakeup from sleep at button activation for as long time as
> > needed to complete a message after release of the button.
> >
> > b) use a low cost 7805 regulator or a zener which draws to much current to
> > be allways on. Thus, the buttons need to switch the power directly and the
> > PIC needs to hold the power in the ON-state via some transistors. After
> > completion it could cut itself and also the stabilizing circuit from power
> > by releasing the transistors.
> >
> > Is there a third possibility i dont think of?  I feel that from the two
> > mentioned either has its drawbacks in a low cost radio control? What would
> > the gurus advice?
> >
> > Germain Morbe
> >
> > --
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>
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>
>

>
> that's exactly what I did, using a MAX619 chip, just needs two .1uF caps.
> This was to get 5v from two AA cells though, but the principle is the
> same.  A button press activates it, then a pin on the pic holds it on
> until it decides to turn it off.  Needs a bit of thinking about or the pic
> will think the button is permanently pressed if you just drive the
> same line.  Nothing a few transistors can't fix.
>
> Martin
>
> TakeThisOuTPICLISTEraseMEspam_OUTMITVMA.MIT.EDU
>
> > This may not fit into your design, but there are low power switching
> > regulators which require fewer components than a typical switching design,
> > and feature shut-down modes which reduce current draw to the uA range.  A
> > button could supply enough power to the shutdown to start it up, and the
> > uC could shut it down as long as the button is not pressed.
> >
> > You might try this one, for instance...
> > dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=1155&Fam=DCDC_All&TREE=PowerSupplies.asp&HP=PowerSupplies.cfm
> >
> > -Adam
> >
> > Germain Morbe wrote:
> > >
> > > Hello,
> > >
> > > has anyone a LOW COST / LOW CURRENT idea that could help solving the
> > > following alimentation problem?
> > >
> > > A 16C505 or 12C508 shall be used as an ecoder for a 12V battery powered 3
> > > button handheld transmitter. Because of the needed code completion feature
> > > after button release, the power must be present permanently / resp. as long
> > > as the PIC needs it.
> > >
> > > The two approaches i see are:
> > >
> > > a) use a very low power 5V regulator which is comparable expensive.  That
> > > way the PIC could wakeup from sleep at button activation for as long time as
> > > needed to complete a message after release of the button.
> > >
> > > b) use a low cost 7805 regulator or a zener which draws to much current to
> > > be allways on. Thus, the buttons need to switch the power directly and the
> > > PIC needs to hold the power in the ON-state via some transistors. After
> > > completion it could cut itself and also the stabilizing circuit from power
> > > by releasing the transistors.
> > >
> > > Is there a third possibility i dont think of?  I feel that from the two
> > > mentioned either has its drawbacks in a low cost radio control? What would
> > > the gurus advice?
> > >
> > > Germain Morbe
> > >
> > > --
> > > http://www.piclist.com hint: To leave the PICList
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> >
>
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>
> Hello,
>
> has anyone a LOW COST / LOW CURRENT idea that could help solving the
> following alimentation problem?
>
> A 16C505 or 12C508 shall be used as an ecoder for a 12V battery powered 3
> button handheld transmitter. Because of the needed code completion feature
> after button release, the power must be present permanently / resp. as long
> as the PIC needs it.
>
> The two approaches i see are:
>
> a) use a very low power 5V regulator which is comparable expensive.  That
> way the PIC could wakeup from sleep at button activation for as long time as
> needed to complete a message after release of the button.
>
> b) use a low cost 7805 regulator or a zener which draws to much current to
> be allways on. Thus, the buttons need to switch the power directly and the
> PIC needs to hold the power in the ON-state via some transistors. After
> completion it could cut itself and also the stabilizing circuit from power
> by releasing the transistors.
>
> Is there a third possibility i dont think of?  I feel that from the two
> mentioned either has its drawbacks in a low cost radio control? What would
> the gurus advice?
>
> Germain Morbe

>
> Jinx,
>
> we buy a seiko ldo that do 100mA, it is about 0,23$ at 10k pcs.
> Its not that cheap but its main drawback is its poor availability over time.
> Once you have decided for such a part you often cannot change on the fly,
> especially at higher volumes.
> That is why our company would love to use no specialized parts at all which
> is often not a technical but a vital decision. I myself prefer state of the
> art components when needed.
>
> In generally i agree to you labour cost arguments, only because its all
> surface mount, labour cost is not that high.
>
> The battery is a small 23A type, usually its voltage not much higher than
> 12V.
>
> We are allowed to radiate up to +10 dBm at 433MHz here in europe, but
> usually with a poor antenna you will be happy to reach 0dBm if you put 100mW
> in.
>
> For the moment i tend to the ldo approach also. Who is building the LP2951?
>
> Germain
>
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>
> > Is there a third possibility i dont think of?  I feel that from the two
> > mentioned either has its drawbacks in a low cost radio control? What would
> > the gurus advice?
>
> I don't know what it costs, but is PIC16HV540 worth considering ?
> It may end up being cheaper to use that and no regulator.
>
> Steve.
> ======================================================
> Steve Baldwin                Electronic Product Design
> TLA Microsystems Ltd         Microcontroller Specialists
> PO Box 15-680, New Lynn      http://www.tla.co.nz
> Auckland, New Zealand        ph  +64 9 820-2221
> email: KILLspamstevebspamBeGonetla.co.nz      fax +64 9 820-1929
> ======================================================
>
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