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'[EE]: How to efficiently run a PIC from 12V batter'
2005\06\30@200845 by Steve Murphy

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face
I need some guidance on how to run a 3-5v PIC circuit efficiently from a
12V, 12A-type (Radio Shack 23-144) battery. (The case I want to use is
designed specifically for this battery).

The enclosure is a Teko 12123.9 key-fob
(http://www.tekoenclosures.com/enclosures/pocket-keyfob.htm). The device
is similar to the little Tamagotchi "pets" that Japanese children play
with. If you've never heard of these, they are little electronic devices
that the children have to pay attention to (push the buttons on it)
periodically or the "pet" gets unhappy. Mine will be simple because I
won't have an LCD screen, just a couple buttons, PIC, an LED or two and
perhaps a beeper or a vibrating pager motor. (I understand that the
pager motor may be a bit of a wild card since it is so power hungry and
I'm interested in conserving power--I may not find one small enough for
this case anyway).

Most of the time the PIC will be in sleep mode, and I will probably just
flash an LED (and/or beep, and/or vibrate the pager motor) for a few
seconds 1-6 times an hour. Should I just use a standard 5V regulator?
But if I do this, won't it be using more power than the rest of the
circuit because it will be dropping 7 V at the same current level as the
rest of the circuit?

Sorry I'm a bit clueless about this. I'm fairly new to PICs and to
power-sensitive apps.

 --Steve Murphy

2005\06\30@202857 by Dwayne Reid

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At 06:08 PM 6/30/2005, Steve Murphy wrote:
>I need some guidance on how to run a 3-5v PIC circuit efficiently from a
>12V, 12A-type (Radio Shack 23-144) battery. (The case I want to use is
>designed specifically for this battery).

I'm sure that you will get many good suggestions.

The one I'm about to offer may not be that good but is worth considering
nonetheless: use a "N" cell instead of the 12V battery.  It's a 1.5V
battery and not much good for anything PIC related until you add one of the
neat Maxim or LTC single-cell step-up convertors.  However, you now have a
much better and stiffer source of power than can be achieved from one of
those 12V batteries.

I'm not up to speed on quiescent current or any of the other important
things you will need to consider if you go this route but the data sheets
are at the manufacturer's web-sites.

dwayne

--
Dwayne Reid   <spam_OUTdwaynerTakeThisOuTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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2005\06\30@203508 by Philip Pemberton

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In message <.....42C4898B.4020103KILLspamspam@spam@cableone.net>
         Steve Murphy <stephmurspamKILLspamcableone.net> wrote:

> Should I just use a standard 5V regulator?

If you mean a linear-mode regulator, I wouldn't. Not when you're dropping 7V.
All that power has to go somewhere (heat!).

Have a look at Roman Black's minimal-parts switchmode regulator - it's on
<http://www.romanblack.com> IIRC. Easy enough to add to an SMD board, as long as you
can get a small enough inductor.

Later.
--
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
.....philpemKILLspamspam.....philpem.me.uk              | ViewFinder, 10BaseT Ethernet, 2-slice,
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... See that slate, That's your keyboard that is.


'[EE]: How to efficiently run a PIC from 12V batter'
2005\07\01@002930 by Steve Murphy
flavicon
face

>>I need some guidance on how to run a 3-5v PIC circuit efficiently from
>>a 12V, 12A-type (Radio Shack 23-144) battery. (The case I want to
>>use is designed specifically for this battery).
>>    
>>
>
>Do you actually need a 12V supply ? LDO micro-current regulators
>I've seen (MCP1700 for example, 1uA active) have an input limit of
>6V or 10V
>
No, I DON'T need 12V. I don't WANT 12V. It's just that the enclosure I'd
like to use is designed to fit a 12V Key FOB battery (it has a bulge
where the battery rests in the enclosure). I went to Radio Shack and
looked for a lithium cell that would fit the enclosure, but none of them
are small enough (except for the coin cells, which kind of defeat the
purpose of this enclosure.

Dwayne suggested a single-cell step-up converter and an N cell (thanks,
Dwayne) something I didn't know that you could do. It looks like it
might work out really well. The only fly in the ointment is that the N
cell is a bit larger than the A23, which fits my enclosure pretty
snugly, so I'll have to go buy an N cell in the morning and try it out.

 --Steve.

2005\07\01@005859 by Steve Murphy

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>>Should I just use a standard 5V regulator?
>>    
>>
>
>If you mean a linear-mode regulator, I wouldn't. Not when you're dropping 7V.
>All that power has to go somewhere (heat!).
>
>Have a look at Roman Black's minimal-parts switchmode regulator - it's on
><http://www.romanblack.com> IIRC. Easy enough to add to an SMD board, as long as you
>can get a small enough inductor.
>  
>
You DID recall correctly (http://www.romanblack.com/smps.htm) and that
page is a real GEM! Amazingly simple and inexpensive circuits but also
very efficient. Very cool. I like how he shows several adaptations of
the circuit, cheapest, best regulation, best all-around. Nice site. Thanks!

2005\07\01@012928 by Jinx

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> >Do you actually need a 12V supply ? LDO micro-current regulators
> >I've seen (MCP1700 for example, 1uA active) have an input limit of
> >6V or 10V
> >
> No, I DON'T need 12V. I don't WANT 12V

OK OK, only asked

> are small enough (except for the coin cells, which kind of defeat the
> purpose of this enclosure.

3 x SR45 - 4.5V, 60mAh

http://www.atcbattery.com/index.cfm?fuseaction=browse&id=11826&pageid=98

2005\07\01@024221 by Steve Murphy

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Jinx wrote:

{Quote hidden}

Sorry, I wasn't upset... I guess I shouldn't use caps for emphasis.

{Quote hidden}

Good point. I saw button cells at RS but I sort of discounted stacking
them. But after seeing the hoops that I need to jump through to make the
other two options work (N-cell or 12V remote battery) this might be my
best bet. I was hoping for the power density of a lithium cell in case I
use a pager motor. But if I don't use the pager motor, these should work
great.

 --Steve.

2005\07\01@040300 by William Chops Westfield

face picon face

On Jun 30, 2005, at 9:29 PM, Steve Murphy wrote:

> No, I DON'T need 12V. I don't WANT 12V. It's just that the
>  enclosure I'd like to use is designed to fit a 12V Key FOB battery

You might get away with a couple of the 1/3AAA or a single 2/3AAA
sized batteries used in some remote control applications (like
inside those hotwheel-sized remote control cars.  See:
   homepage.mac.com/westfw/PhotoAlbum2.html
Only in NiCd (~50mAH) and NiMH (~140mAH), as far as I know, so rather
questionable shelf life (due to self-discharge) but pretty common in
hobby stores or from mail order, ie:
   http://www.maxamps.com/ (loose cells)

The A23 cell is essentially 10 tiny button batteries in an outer
casing (10.3mm).  There's a standard button cell diameter of 9.5mm,
and depending on how much trouble and expense you're willing to go
to, you'd be able to put together your own 4.5 to 6V pack using
slightly less tiny button cells, for significantly better capacity
at your desired voltage.   A type 394 watch battery (PROBABLY available
in alkaline (general purpose), silver (camera), and zinc air (hearing
aid) with slightly different part numbers) is 3.6mm tall (so you
couldn't fit 10 of them in the space of a A23, but 4 and a spacer
would be no problem) and has about twice the mAh capacity.

Type cr927 lithium coin cells are also 9.5mm in diameter or so, and
popular in those novelty blinking LED pins and such, which means
that they are available (in bulk) at relatively low prices compared
to typical specialty batteries.  Capacity is slightly less than the
A23, though...

BillW

2005\07\01@044205 by Steve Murphy

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> to, you'd be able to put together your own 4.5 to 6V pack using
> slightly less tiny button cells, for significantly better capacity
> at your desired voltage...

It's funny, when you mentioned this it jogged loose in my memory a site
I recently visited that described doing precisely this, ironically with
the exact 12V  remote battery that prompted my original question:

http://members.cox.net/berniekm/battery.html

It's clever how he used a couple of washers and some heat shrink tubing
to make his own custom battery pack, just as you suggest.

Thanks,

 --Steve.

2005\07\01@050044 by Jinx

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> Sorry, I wasn't upset... I guess I shouldn't use caps for emphasis.

My apology too if I came over as grumpy (but boy has it been a
frustrating week ! and it ain't done yet, groan)

> >3 x SR45 - 4.5V, 60mAh

It's probable that the DIY pack you and WCW mentioned is based
on something like the SR45, given the diameter. This might be a shot
in the dark, but if you stripped the wrapper off a 12A......what would
you find ? Worth a punt ?

2005\07\01@053410 by Jan-Erik Soderholm

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William "Chops" Westfield wrote :

> A type 394 watch battery
(PROBABLY
> available in alkaline (general purpose), silver (camera),
> and zinc air (hearing aid) with slightly different part numbers)
> is
3.6mm tall (so you couldn't fit 10 of them in the space of a
> A23, but
4 and a spacer would be no problem) and has
> about twice the mAh
capacity.

Hi.
Just thinking out loud here...

Other posts have also
been talking about getting a lower
voltage battery with a higher mAh
value (in this case "twice"
the capacity).

Now, Let's say we have a
12V/100mAh battery and one
4.5/200mAh battery. Now, the 4.5V battery
*seems* to have
double capacity (which most equals with "lifetime"
under
similar conditions). But, if using a well designed step-down
converter, will that not draw *less* current from the higher
voltage
source, then the target is using ? Or in other words,
if one could
expect a 100% efficient converter, is it not realy
the V x mAh value
that is interesting, not ? Even if the
converter runs at something like
80-85%, I think that
one can not just compare the mAh values
directly...

I'm not claiming to be an expert in this, just liked to
know...

Jan-Erik.



2005\07\01@054424 by Michael Rigby-Jones

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{Quote hidden}

You are correct, the total energy available from a 12v 100mAh battery is greater than that from a 4.5 200mAh battery.  The only way to make use of the extra eneregy is, as you suggest, a switching converter.  Obviously a 100% efficienct converter does not exist, but they can achieve very high efficiencies.  If the design can tolerate the cost, board space and potential noise of the switcher then it may be a good solution.

Regards

Mike

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2005\07\01@055042 by Jinx

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> if one could expect a 100% efficient converter, is it not realy
> the V x mAh value that is interesting, not ?

You mean comparing the batteries in terms of mWh ? In the end
I suppose it boils down to the number of electrons available and
the internal resistance of the battery. But I wouldn't know where
to take it from there. The practical problem is the step-down
efficiency

2005\07\01@055344 by Russell McMahon

face
flavicon
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As long as cost is not an utterly compelling factor, and it's not
likely to be:     Choose a battery that, regardless of voltage, and
given physical and mechanical constraints, best meets *your* needs for
energy capacity, rechargeability, self discharge rate etc. THEN choose
a suitable available modern power converter IC or other cct to process
its output. These may be boost, buck or buck-boost depending on what
the optimum battery looks like. ALL converters will be able to be
small, including inductor and glue components. Some options may be
more costly than others, but for a one off project any of the
topologies will be able to be done at a price that is reasonable for
the convenience they provide.  Best battery maybe , but almost
certainly won't be, under about 2v minimum for efficiency purposes.

So, choose your optimum battery and THEN we can start on the best
converter.



       RM

2005\07\01@055827 by William Chops Westfield

face picon face

On Jul 1, 2005, at 2:34 AM, Jan-Erik Soderholm wrote:

> Now, Let's say we have a 12V/100mAh battery and one
> 4.5/200mAh battery. Now, the 4.5V battery *seems* to have
> double capacity (which most equals with "lifetime" under
> similar conditions). But, if using a well designed step-down
> converter, will that not draw *less* current from the higher
> voltage source, then the target is using ?

Yes.  For a suitably "well designed switching step-down converter",
which is more than trivial to design.  ACTUAL battery capacity is
in Watt-hours, or V*mAH.  But your circuit will always be most
efficient if you can operate directly off battery voltage, with
no regulators at all, and you need to consider the whole circuit
if you're aiming to maximize battery life.  I think it was linear
technology who pointed out some time ago that running 2 AA batteries
to a 5V step-up regulator provided MUCH better capacity in "about"
the same space as a 9V battery with a 5V linear regulator...

BillW

2005\07\01@060852 by Steve Murphy

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face

>>>3 x SR45 - 4.5V, 60mAh
>>>      
>>>
>
>It's probable that the DIY pack you and WCW mentioned is based
>on something like the SR45, given the diameter. This might be a shot
>in the dark, but if you stripped the wrapper off a 12A......what would
>you find ? Worth a punt ?
>
Done. There are eight button cells, about 3mm tall and 9.5 in
diameter--somewhat shorter than the 304 (SR45, a.k.a. 304, a.k.a SR 936
SW, mouser# 614-394). Datasheet found here:
http://www.renata.com/pdf/watch/DB394.04.pdf

Thanks to all for all of the great information. For this application I
think I'll forego the 12V and build my own 6V 84 mAh pack out of four
304 cells and power the circuit directly.

 --Steve.

2005\07\01@062013 by Michael Rigby-Jones

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{Quote hidden}

Not really a fair comparison though, i.e. switcher vs. linear.

>From the Energizer web site, and ignoring voltage drop over life:

1x Alkaline PP3 625mAh  Total energy = 14.4 Wh
2x Alkaline AA  2850mAh Total energy = 8.55 Wh

A PP3 has a significantly higher energy density than 2AA's, so with a suitable buck regulator it may last quite a bit longer than AA's dependant on current draw.  The downside is cost, 9volt "block" batteries such as the PP3 are significantly more expensive than AA's.

Regards

Mike

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2005\07\01@063503 by p.cousens

flavicon
Looking at the flat discharge curve for these batteries why not use 3
cells to get 4.6V
And unless you need the space, do it twice to get 168mAH

> {Original Message removed}

2005\07\01@064414 by p.cousens

flavicon
Check the math for the PP3, I make it 5.625 WH

 PC

> -----Original Message-----
> From: spamBeGonepiclist-bouncesspamBeGonespammit.edu
> [TakeThisOuTpiclist-bouncesEraseMEspamspam_OUTmit.edu] On Behalf Of Michael Rigby-Jones
> Sent: Friday, July 01, 2005 11:20 AM
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE]: How to efficiently run a PIC from 12V battery?
snip

{Quote hidden}

2005\07\01@064629 by Jinx

face picon face
> Done. There are eight button cells, about 3mm tall and 9.5 in

Way to go. Here are some tips from Microchip. The nW parts
are what you really want to be using for longest battery life (I've
tested the 12F675 at 7nA SLEEP current)

================================

www.microchip.com/stellent/stellent/idcplg?IdcService=SS_GET_PAGE&nod
eId=1484

Q. How can I make my PIC16/17 run as low power as possible?

A. Section Tips Posted: 10/25/1997 10:35:49 AM Discussion:

1. Run the clock as slow as you can.

2. Disable the watchdog timer

3. Put the part to sleep whenever possible.

4. Use MCLR to wake part from sleep instead of the WDT if possible.

5. Do not let any inputs float.

6. Do not drive any unnecessary loads. Minimize capacitive or inductive
loads on switching I/O pins, or resistive loads on other driven pins. If
a pin is not to be used you can leave it disconnected and drive it low
or high, or put a pull up or down resistor on it as an input.

7. Turn off all timers when not in use. For instance, TMR0 can be
incremented from the instruction clock or an external pin. When not in
use, assign it to the pin (if it is toggling at a lower rate than the
instruction clock). Do not use prescalers when unnecessary. In other
words, minimize the amount of logic changing states.

8. Turn off any other peripherals when not in use

2005\07\01@065709 by Howard Winter

face
flavicon
picon face
On Fri, 1 Jul 2005 11:20:08 +0100, Michael Rigby-Jones wrote:

>...<
> >From the Energizer web site, and ignoring voltage drop over life:
>
> 1x Alkaline PP3 625mAh  Total energy = 14.4 Wh
> 2x Alkaline AA  2850mAh Total energy = 8.55 Wh

Is there a typo there?  0.625 x 9 = 5.625

> A PP3 has a significantly higher energy density than 2AA's

This certainly isn't true for rechargeables - a high-end capacity for a PP3 rechargeable is 250mAh (at 8V4, giving 2.1Wh) whereas 1800mAh is at the low end for an AA (at 2V4 a pair, giving 4.32Wh).  Granted that a pair of AAs is bigger then a PP3, the capacity doesn't account for the difference.

> The downside is cost, 9volt "block" batteries such as the PP3 are significantly more expensive than AA's.

Quite!  Looking at Tantronics site (http://www.tantronics.co.uk) at the top of their ranges, a 250mAh PP3 is £8.50 (£4/Wh), a set of four 2600mAh AAs is £14.95, so say £7.50 a pair (£1.20/Wh), for 2.1 and 6.24 Wh respectively.  If you can put up with only 1800mAh, four AAs are £6.50 (£0.75/Wh)!

I have seen an article proposing that the best use of rechargeables is to use the largest single cell you can get (D?) and a boost regulator... but that's for another discussion  :-)

Cheers,


Howard Winter
St.Albans, Herts

2005\07\01@070418 by Alvaro Deibe Diaz

picon face
What really matters is the energy the battery can supply, and the efficiency
in its use. As you said, V x mAh is more interesting that mAh alone. Volts x
Amperes x time is a measure of the energy the battery can give you:
. 12V,100mAh   ->  12V x 0.1A x 3600s/h=4320J
. 4.5V, 200mAh -> 4.5V x 0.2A x 3600s/h=3240J

So, theoretically, you could get 4320 Joules off the first battery, and 3240
Joules from the second.

This numbers are made supposing the voltage and the current remains constant
during the discharge, but this is not usually the case, so this numbers must
be taken as aproximations only.

If you use an 80% efficient converter to drive the circuit from the 12V
battery, you get 0.8*4320=3456 useful Joules out of the battery, and waste
0.2*4320=864J, which are finally transformed in heat (enthropy) in one way
or another.

In this case, 3456J is slightly better than 3240J.

{Quote hidden}

2005\07\01@071858 by Mike Harrison

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face
On Fri, 01 Jul 2005 22:46:23 +1200, you wrote:

>> Done. There are eight button cells, about 3mm tall and 9.5 in
>
>Way to go. Here are some tips from Microchip. The nW parts
>are what you really want to be using for longest battery life (I've
>tested the 12F675 at 7nA SLEEP current)
>
>================================
>
>www.microchip.com/stellent/stellent/idcplg?IdcService=SS_GET_PAGE&nod
>eId=1484
>
>Q. How can I make my PIC16/17 run as low power as possible?
>
>A. Section Tips Posted: 10/25/1997 10:35:49 AM Discussion:
>
>1. Run the clock as slow as you can.
If running continuously, yes, but if sitting in sleep most of the time and waking up occasionally,
faster clocks can sometimes allow less on-time and therefore less current. You need to do tests as
every application is different and there is no simple answer to which is the optimum rate.

For example, I did some tests on a 16F636, INTRC waking every 30ms and executing a short loop 16
times :

31K : 6.4 uA (awake 12ms)
125K : 17 uA
250K : 10.1 uA (awake 1.5ms)
500K : 6.5 uA
1M : 4.6 uA
2M : 3.6 uA
4M : 3.1 uA
8M : 2.9 uA (awake 46uS)

The above was at 3.6V and INCLUDES the WDT current!

The other neat thing on the nanopower parts is you can change the clock speed as required,
on-the-fly. e.g. if you need a few tens or hundreds of of microseconds' delay, just kick the clock
down to 125K or 31K for a few cycles.  

>2. Disable the watchdog timer

Nanopower parts have MUCH better WDT power draw, and a lot of flexibility on WDT interval, both
faster and slower than the older parts - from memory it's something like 1ms to a minute or so.

>3. Put the part to sleep whenever possible.

But if using xtals or resonators remember that there is a time (and therefore power) associated with
wakeup

>4. Use MCLR to wake part from sleep instead of the WDT if possible.
Pin-change interrupts are also good.

>5. Do not let any inputs float.

A 'quick test' for this is to run your finger (or a finger-held probe) along the pins while watching
the current consumption. Mains hum going into a floating pin will produce at least 10s of microamps.
A more scientific test is to apply a 10-ish khz sinewave swinging within the supply rails via a 1M
resistor to each pin in turn. A floating input will give a noticeable (>10uA) increase in current
draw.

One they missed on that list - run at the lowest voltage you can.


2005\07\01@072252 by Michael Rigby-Jones

picon face


>-----Original Message-----
>From: RemoveMEpiclist-bouncesspamTakeThisOuTmit.edu [piclist-bouncesEraseMEspam.....mit.edu]
>Sent: 01 July 2005 11:46
>To: 'Microcontroller discussion list - Public.'
>Subject: RE: [EE]: How to efficiently run a PIC from 12V battery?
>
>
>Check the math for the PP3, I make it 5.625 WH
>
>  PC


Oops!  That's what you get for having fingers much bigger than calculator buttons ;)

Regards

Mike

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2005\07\01@073019 by Jinx

face picon face
> One they missed on that list - run at the lowest voltage you can.

You make some good points. Note that those FAQs apparently
originate from 1997, much-improved technology and many new
features since then of course

2005\07\01@073809 by Jinx

face picon face
> Nanopower parts have MUCH better WDT power draw, and a lot of
> flexibility on WDT interval, both faster and slower than the older parts -
> from memory it's something like 1ms to a minute or so

The F88 is 1ms to 268s (4m28s)

It's a very versatile device, possibly a little daunting as an introduction
to PICs though



2005\07\01@124058 by Steve Murphy

flavicon
face

{Quote hidden}

Exactly. Now the fun begins!  :-)

BTW, I didn't realize the 12F675 was a nW device... and how did you
manage to *measure* 7 nA?

2005\07\01@124758 by Mark Rages

face picon face
On 7/1/05, Steve Murphy <EraseMEstephmurspamcableone.net> wrote:

> BTW, I didn't realize the 12F675 was a nW device... and how did you
> manage to *measure* 7 nA?

Millivolt meter and 1 megohm resistor?

Regards,
Mark
markrages@gmail
--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\07\01@125147 by Steve Murphy

flavicon
face

>Looking at the flat discharge curve for these batteries why not use 3
>cells to get 4.6V
>And unless you need the space, do it twice to get 168mAH
>  
>
This is a very good point. But contemplating getting in the battery
packaging business, I have a whole new respect for the lowly CR2032
button cell. 225 mAh @ 3V for 33 cents in a nice small package.

In the clear light of day I'm realizing that what's crazy about this
whole process is that it is an example of the tail wagging the dog. I
liked the enclosure but it didn't seem to fit a 2032 so I started
exploring use of the much more expensive 12V the case is designed to
accommodate and I have been "chasing my tail" ever since. (But now I'm
mixing metaphors. ;-)

In a flip-flop from what I said last night, I think I need to shoehorn
in a CR2032 into the enclosure or abandon the enclosure entirely (there
are at least a dozen others to choose from). I'm pretty sure I don't
want to be in the battery mfg business.

 --Steve.

2005\07\01@125429 by Steve Murphy

flavicon
face


Mike Harrison wrote:

{Quote hidden}

Thanks. This goes into my bin of list emails never to delete. All the
low power tips (and nW modes and techniques) seem daunting, but
individually they seem achievable. Wish me luck!  :-)

 --Steve.

2005\07\01@134452 by Jan-Erik Soderholm

face picon face
Steve Murphy wrote :

> BTW, I didn't realize the
> 12F675 was a nW
device...

Neither the 12F675 or the
12F629 are. The 12F683 is.

Jan-
Erik.



2005\07\01@134916 by Jan-Erik Soderholm

face picon face
Mike Harrison wrote :

> >3. Put the part to sleep whenever possible.
>
> But if using xtals or resonators remember that there is a
> time
(and therefore power) associated with
> wakeup

You can run it in
"double-speed-startup" where
it runs (directly) from the intosc until
the
main osc is stable. For short runs you might
be back in sleep
before the main osc has
started. For others "sessions" where you have
(e.g.) serial comms, you can wait for the main osc
to startup (there is
a flag to watch).

Jan-Erik.




2005\07\01@135805 by Jan-Erik Soderholm

face picon face
Steve Murphy wrote :

> Thanks. This goes into my bin of list emails
never to delete. All the
> low power tips (and nW modes and
techniques) seem daunting, but
> individually they seem achievable.
Wish me luck!  :-)

Also check :

http://ww1.microchip.
com/downloads/en/AppNotes/00879b.pdf

http://ww1.microchip.
com/downloads/en/DeviceDoc/41200B.pdf

Jan-Erik.



2005\07\01@171133 by Jinx

face picon face
> > BTW, I didn't realize the
> > 12F675 was a nW
> device...
>
> Neither the 12F675 or the
> 12F629 are. The 12F683 is.

Microchip may describe just the 12F683 as nW, but compare its
power figures with the 12F629/675. In some cases the latter is
better. eg parameters D021 (WDT current), D015 etc (run uA
at various frequencies). I'm sure it's a case of the documentation
not reflecting the true capabilities of the part. Microchip have the
16F628A on their list of nW parts, but I've never considered it nW
(not according to my DS anyway)


www.microchip.com/ParamChartSearch/chart.aspx?branchID=103&mid=10&lan
g=en&pageId=74

2005\07\01@181410 by Jan-Erik Soderholm

face picon face
Jinx wrote :

> >
> > Neither the 12F675 or the
> > 12F629 are. The
12F683 is.
>
> Microchip may describe just the 12F683 as nW, but
compare its
> power figures with the 12F629/675. In some cases the
latter is
> better. eg parameters D021 (WDT current), D015 etc (run uA
> at various frequencies).

I've never coupled "nanoWatt" to the fact
that some
Dxxx-parameters should be better on those devices
then on
other devices.

But rather to the fact that they have such features as
1% intosc, an intosc "gearbox" with 8 steps, WDT with
a larger range,
two-speed startup and so on. And in
those cases what I wrote about the
12F's is correct.

Now, since the 12F683 has twice the flash, much more
RAM,
more peripherials and so on, I'm not surpriced that one
can find
some parameters that are "worse" compared
with the older 12F's with
less flash, less RAM and
less features in general.

Best Regards,
Jan-
Erik.



2005\07\01@184020 by Jinx

face picon face
> > better. eg parameters D021 (WDT current), D015 etc (run uA
> > at various frequencies).
>
> I've never coupled "nanoWatt" to the fact that some Dxxx-parameters
> should be better on those devices then on other devices

But doesn't "nanoWatt" imply that the part should use less power ?
Maybe I over-simplified the case for the 12F675 vs the 12F683. I can't
see one power parameter for the 683 that's better than the 675 (possibly
I've missed something)

> But rather to the fact that they have such features as 1% intosc, an
> intosc "gearbox" with 8 steps, WDT with a larger range, two-speed
> startup and so on. And in those cases what I wrote about the 12F's
> is correct

The 683 is obviously more fully-featured (which you pay for, naturally)
than the 675 , but specifically apropos The Subject, the12F675 is a
perfectly good example of a nW part. Microchip have simply omitted it
from the list of parts they describe as nW. IMHO that list is neither
complete
nor correct (as noted previously, 12F675 excluded, 16F628A included)

> Now, since the 12F683 has twice the flash, much more RAM, more
> peripherials and so on, I'm not surpriced that one can find some
> parameters that are "worse" compared with the older 12F's with less
> flash, less RAM and less features in general

By that same argument then, you'd expect that the same core with fewer
features would use less power. Which it does, so is not the 12F675 nW ?

2005\07\01@201221 by William Chops Westfield

face picon face

On Jul 1, 2005, at 3:40 PM, Jinx wrote:

> But doesn't "nanoWatt" imply that the part should use less power ?
>

Nah, "nanoWatt" is a sort of tradename for a set of features aimed
at letting engineers design things that consume less power.
(probably in direct response to MSP430 pressures :-)

In fact, this is one of the things that I think microchip has done
well compared to other microcontroller vendors - made the features
(peripheral-wise) orthogonal with other things like RAM, PROM, and
pin count...

BillW

2005\07\01@201222 by William Chops Westfield

face picon face

On Jul 1, 2005, at 2:11 PM, Jinx wrote:

> Microchip may describe just the 12F683 as nW, but compare its
> power figures with the 12F629/675. In some cases the latter is
> better. eg parameters D021 (WDT current), D015 etc (run uA
> at various frequencies). I'm sure it's a case of the documentation
> not reflecting the true capabilities of the part.

Doesn't "nanowatt" mean that the chip has a set of features aimed at
low power operation - switchable clocks, variable WDT, stuff like
that?  The 12f675 may have very low power consumption, but it doesn't
have the specific features that make a part "nanowatt"...

BillW

2005\07\01@210543 by Jinx

face picon face
> Doesn't "nanowatt" mean that the chip has a set of features aimed at
> low power operation - switchable clocks, variable WDT, stuff like
> that?  The 12f675 may have very low power consumption, but it
> doesn't have the specific features that make a part "nanowatt"...

Well, I guess it's coming down to semantics. Who, apart from MC
themselves, actually knows what is, or was originally, meant by the
term "nanoWatt". Perhaps they do mean a drastic current reduction
in peripherals. To my mind though, the 12F675 is so close to the
12F683 that it should be classed as nW. Because in truth that is what
it actually consumes. So I don't consider it wrong to call it a nW part.
Some "nW" parts have fewer peripherals than the 12F675. If you don't
use most of those peripherals, as could well be the case, then what
you're left with is base consumption. Whatever, you pick the part that
suits your needs of course, however it's been pigeon-holed

2005\07\01@220210 by William Chops Westfield

face picon face
>> Doesn't "nanowatt" mean that the chip has a set of features aimed at
>> low power operation

Well...

http://www.microchip.com/stellent/groups/designcenter_sg/documents/
designcenter/en500064.pdf  "What is nanoWatt echnology"

not as feature-specific as I thought, but "managed multiple clock
sources" is explicitly included...

BillW

2005\07\01@224617 by Jinx

face picon face
>> Doesn't "nanowatt" mean that the chip has a set of features aimed at
>> low power operation
>
> Well...
>
> http://www.microchip.com/stellent/groups/designcenter_sg/documents/
> designcenter/en500064.pdf  "What is nanoWatt echnology"

nanoWatt Technology entails four key elements:

(a) the PMOS Electrical Erasable Cell (PEEC)
(b) new circuit design techniques
(c) enhanced manufacturing techniques
(d) optimal field support

There's a lot of ad-speak in that pdf, but, y'know, good on them, it's
all about market share. Anyone discerning enough would be looking
past that anyway. I wouldn't say (d) has anything to do with making a
chip perform better. (c) "New circuit design techniques that are unique
to nanoWatt Technology include brown-out and low voltage detect" -
not exactly new is it ? But, look, I don't want to get in anyone's face.
A selectable clock and improved fabrication patently is a good way to
reduce power. MC just happen to have chosen a name that doesn't
quite fit IMVHO

2005\07\02@085038 by olin piclist

face picon face
Jinx wrote:
> Well, I guess it's coming down to semantics. Who, apart from MC
> themselves, actually knows what is, or was originally, meant by the
> term "nanoWatt".

Keep in mind this term comes from the *marketing* department.  Need we say
more?


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\07\02@093752 by Jan-Erik Soderholm

face picon face
Jinx wrote :


> Perhaps they do mean a drastic current reduction
> in
peripherals.

I don't think so, but I might be wrong.

> To my mind
though, the 12F675 is so close to the
> 12F683 that it should be
classed as nW.

No, it lacks many of the "nW" features, such as all
INTOSC "nW-options".

> So I don't consider it wrong to call it a nW
part.

OK, fine.
I prefer to follow the definitions set up by MC, that
makes it much easier to read (e.g.) the link-card.
And when I see
"nanoWatt" on the first page of
the data sheet, I know that this part
has some
specific core/osc features.

> Some "nW" parts have fewer
peripherals than the 12F675.

So what ?
"nW" is about core/osc
features, not peripherials.
"nW" doesn't imply that the part has some
specific
peripherial(s), does it ?

Best Reagrds,
Jan-Erik.



2005\07\02@100025 by Jinx

face picon face
> OK, fine.
> I prefer to follow the definitions set up by MC, that
> makes it much easier to read (e.g.) the link-card

OK, fine. ;-) The 16F628A is now nW because MC says it is

> > Some "nW" parts have fewer
> peripherals than the 12F675.
>
> So what ?

> "nW" is about core/osc features, not peripherials. "nW" doesn't
> imply that the part has some specific peripherial(s), does it ?

I don't know - it's not me claiming that peripherals make a nW
part nW. I've only ever mentioned what current the device actually
uses. Which, in the end, is all I care about. MC can call it whatever
the heck they like


2005\07\02@102935 by Russell McMahon

face
flavicon
face
I'm surprised that Jan-Erik is using the wrong tag here ;-) ;-) ;-)
;-) ;-)

How about moving this thread ONTO [PIC] to save noising up [EE] ?
(and/or changing the subject line).

As they always say, I'd have posted this on PIC but nobody following
the revised thread would have noticed it ;-)


   RM

...
> I prefer to follow the definitions set up by MC, that
...
etc



2005\07\02@201507 by Jinx

face picon face
> How about moving this thread ONTO [PIC] to save noising up [EE] ?
> (and/or changing the subject line).

I think it's run its course anyway. There are obviously two intractable
schools of thought. The voice of reason (me) and ...... everybody else ;-)

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