Forums

Power solutions for 9V battery

Started by Douglas Beeson July 21, 2014
Hi all,

I need to generate +15 V and -15 V (just a few mA), as well as standard 5V (about 50 mA), from a 9V battery. I am bewildered by the range of solutions available. I have used LDOs many times, but am discouraged by their low efficiency for this battery-powered project.

I have looked at the LT1054 capacitor-based voltage regulator, and like its simplicity and ability to generate both + and - 15V from the same circuit, but the diode losses and internal losses mean that as the 9V discharges my output will fall to only 11 V or so, which is insufficient.

I can't seem to find an easy way to get -15V from +9V without a gazillion external parts.

What do you all suggest?

thanks,
doug
On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

>Hi all, > >I need to generate +15 V and -15 V (just a few mA), as well as standard 5V (about 50 mA), from a 9V battery. I am bewildered by the range of solutions available. I have used LDOs many times, but am discouraged by their low efficiency for this battery-powered project. > >I have looked at the LT1054 capacitor-based voltage regulator, and like its simplicity and ability to generate both + and - 15V from the same circuit, but the diode losses and internal losses mean that as the 9V discharges my output will fall to only 11 V or so, which is insufficient. > >I can't seem to find an easy way to get -15V from +9V without a gazillion external parts. > >What do you all suggest? > >thanks, >doug
See... OldStyleBuckSwitcherWithAddedNegativeOutput.pdf on the S.E.D/Schematics page of my website for a starting point. I first used that scheme in the early '80's. I'd probably clock it now for better control and stability. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On 7/21/2014 8:42 AM, Douglas Beeson wrote:
> Hi all, > > I need to generate +15 V and -15 V (just a few mA), as well as standard 5V (about 50 mA), from a 9V battery. I am bewildered by the range of solutions available. I have used LDOs many times, but am discouraged by their low efficiency for this battery-powered project. > > I have looked at the LT1054 capacitor-based voltage regulator, and like its simplicity and ability to generate both + and - 15V from the same circuit, but the diode losses and internal losses mean that as the 9V discharges my output will fall to only 11 V or so, which is insufficient. > > I can't seem to find an easy way to get -15V from +9V without a gazillion external parts. > > What do you all suggest? > > thanks, > doug >
I hope your app is very intermittent use. I doubt you will get 4 hrs at 50 ma. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com
On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson wrote:

> Hi all, > > I need to generate +15 V and -15 V (just a few mA), as well as standard > 5V (about 50 mA), from a 9V battery. I am bewildered by the range of > solutions available. I have used LDOs many times, but am discouraged by > their low efficiency for this battery-powered project. > > I have looked at the LT1054 capacitor-based voltage regulator, and like > its simplicity and ability to generate both + and - 15V from the same > circuit, but the diode losses and internal losses mean that as the 9V > discharges my output will fall to only 11 V or so, which is > insufficient. > > I can't seem to find an easy way to get -15V from +9V without a > gazillion external parts. > > What do you all suggest?
The first thing that I suggest is that you not use a 9V battery. I don't have my reference materials here to quote exact figures, but there's significantly more useful energy in a pair of AA cells than in a 9V battery, for not much weight or space. I'd find the most efficient switcher chip that I can find that'll boost 3.5 to 1.8V up to 5V, and then use either switchers or switched-capacitor chips to go from +5V to +/- 15V. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
On Mon, 21 Jul 2014 11:16:32 -0500, Tim Wescott wrote:

> On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson wrote: > >> Hi all, >> >> I need to generate +15 V and -15 V (just a few mA), as well as standard >> 5V (about 50 mA), from a 9V battery. I am bewildered by the range of >> solutions available. I have used LDOs many times, but am discouraged by >> their low efficiency for this battery-powered project. >> >> I have looked at the LT1054 capacitor-based voltage regulator, and like >> its simplicity and ability to generate both + and - 15V from the same >> circuit, but the diode losses and internal losses mean that as the 9V >> discharges my output will fall to only 11 V or so, which is >> insufficient. >> >> I can't seem to find an easy way to get -15V from +9V without a >> gazillion external parts. >> >> What do you all suggest? > > The first thing that I suggest is that you not use a 9V battery. I > don't have my reference materials here to quote exact figures, but > there's significantly more useful energy in a pair of AA cells than in a > 9V battery, for not much weight or space. I'd find the most efficient > switcher chip that I can find that'll boost 3.5 to 1.8V up to 5V, and > then use either switchers or switched-capacitor chips to go from +5V to > +/- 15V.
From my Radio Shack battery guide, it looks like an apples-to-apples comparison of 9V batteries with a pair of AA batteries gets you about ten times more life out of the AA batteries. Even a pair of AAA batteries looks like it'll get you four times the life. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
On Mon, 21 Jul 2014 13:11:53 -0500
Tim Wescott <tim@seemywebsite.really> wrote:

> On Mon, 21 Jul 2014 11:16:32 -0500, Tim Wescott wrote: > > > On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson wrote: > > > >> Hi all, > >> > >> I need to generate +15 V and -15 V (just a few mA), as well as standard > >> 5V (about 50 mA), from a 9V battery. I am bewildered by the range of > >> solutions available. I have used LDOs many times, but am discouraged by > >> their low efficiency for this battery-powered project. > >> > >> I have looked at the LT1054 capacitor-based voltage regulator, and like > >> its simplicity and ability to generate both + and - 15V from the same > >> circuit, but the diode losses and internal losses mean that as the 9V > >> discharges my output will fall to only 11 V or so, which is > >> insufficient. > >> > >> I can't seem to find an easy way to get -15V from +9V without a > >> gazillion external parts. > >> > >> What do you all suggest? > > > > The first thing that I suggest is that you not use a 9V battery. I > > don't have my reference materials here to quote exact figures, but > > there's significantly more useful energy in a pair of AA cells than in a > > 9V battery, for not much weight or space. I'd find the most efficient > > switcher chip that I can find that'll boost 3.5 to 1.8V up to 5V, and > > then use either switchers or switched-capacitor chips to go from +5V to > > +/- 15V. > > From my Radio Shack battery guide, it looks like an apples-to-apples > comparison of 9V batteries with a pair of AA batteries gets you about ten > times more life out of the AA batteries. Even a pair of AAA batteries > looks like it'll get you four times the life. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com >
I see your point. I just assumed that it was easier to step down to 5 and up to 15 from somewhere in between, but looking at the chips available I see that most solutions address lower-voltage cells. So I will look at AAs. Thanks, Tim. doug -- Douglas Beeson <c.difficile@gmail.com>
On Mon, 21 Jul 2014 07:37:19 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

> On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson > <c.difficile@gmail.com> wrote: > > >Hi all, > > > >I need to generate +15 V and -15 V (just a few mA), as well as standard 5V (about 50 mA), from a 9V battery. I am bewildered by the range of solutions available. I have used LDOs many times, but am discouraged by their low efficiency for this battery-powered project. > > > >I have looked at the LT1054 capacitor-based voltage regulator, and like its simplicity and ability to generate both + and - 15V from the same circuit, but the diode losses and internal losses mean that as the 9V discharges my output will fall to only 11 V or so, which is insufficient. > > > >I can't seem to find an easy way to get -15V from +9V without a gazillion external parts. > > > >What do you all suggest? > > > >thanks, > >doug > > See... > > OldStyleBuckSwitcherWithAddedNegativeOutput.pdf > > on the S.E.D/Schematics page of my website for a starting point. > > I first used that scheme in the early '80's. I'd probably clock it > now for better control and stability. > > ...Jim Thompson > -- > | James E.Thompson | mens | > | Analog Innovations | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | San Tan Valley, AZ 85142 Skype: skypeanalog | | > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > | E-mail Icon at http://www.analog-innovations.com | 1962 | > > I love to cook with wine. Sometimes I even put it in the food.
Thank, Jim. Did you use a microcontroller or something else for gate control? doug -- Douglas Beeson <c.difficile@gmail.com>
On Mon, 21 Jul 2014 15:27:15 -0400, Douglas Beeson wrote:

> On Mon, 21 Jul 2014 13:11:53 -0500 Tim Wescott <tim@seemywebsite.really> > wrote: > >> On Mon, 21 Jul 2014 11:16:32 -0500, Tim Wescott wrote: >> >> > On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson wrote: >> > >> >> Hi all, >> >> >> >> I need to generate +15 V and -15 V (just a few mA), as well as >> >> standard 5V (about 50 mA), from a 9V battery. I am bewildered by the >> >> range of solutions available. I have used LDOs many times, but am >> >> discouraged by their low efficiency for this battery-powered >> >> project. >> >> >> >> I have looked at the LT1054 capacitor-based voltage regulator, and >> >> like its simplicity and ability to generate both + and - 15V from >> >> the same circuit, but the diode losses and internal losses mean that >> >> as the 9V discharges my output will fall to only 11 V or so, which >> >> is insufficient. >> >> >> >> I can't seem to find an easy way to get -15V from +9V without a >> >> gazillion external parts. >> >> >> >> What do you all suggest? >> > >> > The first thing that I suggest is that you not use a 9V battery. I >> > don't have my reference materials here to quote exact figures, but >> > there's significantly more useful energy in a pair of AA cells than >> > in a 9V battery, for not much weight or space. I'd find the most >> > efficient switcher chip that I can find that'll boost 3.5 to 1.8V up >> > to 5V, and then use either switchers or switched-capacitor chips to >> > go from +5V to +/- 15V. >> >> From my Radio Shack battery guide, it looks like an apples-to-apples >> comparison of 9V batteries with a pair of AA batteries gets you about >> ten times more life out of the AA batteries. Even a pair of AAA >> batteries looks like it'll get you four times the life. >> >> -- >> >> Tim Wescott Wescott Design Services http://www.wescottdesign.com >> >> > > I see your point. I just assumed that it was easier to step down to 5 > and up to 15 from somewhere in between, but looking at the chips > available I see that most solutions address lower-voltage cells. So I > will look at AAs. Thanks, Tim.
I do think the best way to get to 15V is from the 5V rail -- but each individual circuit always ends up with its own quirks. I'm going to take the opportunity to voice a pet peeve here: <rant=on> If you do use just two cells, make damned sure that you use a regulator that's good down to 1.8V, or 2V at worst. NiMH and dry cells both are good all the way down to 0.9V/cell: not working down that far is just throwing away useful energy that could go to make your customer happy. </rant> Have fun. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
On Mon, 21 Jul 2014 15:29:38 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

>On Mon, 21 Jul 2014 07:37:19 -0700 >Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote: > >> On Mon, 21 Jul 2014 09:42:10 -0400, Douglas Beeson >> <c.difficile@gmail.com> wrote: >> >> >Hi all, >> > >> >I need to generate +15 V and -15 V (just a few mA), as well as standard 5V (about 50 mA), from a 9V battery. I am bewildered by the range of solutions available. I have used LDOs many times, but am discouraged by their low efficiency for this battery-powered project. >> > >> >I have looked at the LT1054 capacitor-based voltage regulator, and like its simplicity and ability to generate both + and - 15V from the same circuit, but the diode losses and internal losses mean that as the 9V discharges my output will fall to only 11 V or so, which is insufficient. >> > >> >I can't seem to find an easy way to get -15V from +9V without a gazillion external parts. >> > >> >What do you all suggest? >> > >> >thanks, >> >doug >> >> See... >> >> OldStyleBuckSwitcherWithAddedNegativeOutput.pdf >> >> on the S.E.D/Schematics page of my website for a starting point. >> >> I first used that scheme in the early '80's. I'd probably clock it >> now for better control and stability. >> >> ...Jim Thompson
[snip]
> > >Thank, Jim. Did you use a microcontroller or something else for gate control? > >doug
Me? The Analog dance master >:-} Simple-minded hysteretic control, switch on at 4.99V, off at 5.01V, so the switching rate wanders with load... that's why I added the "...probably clock it now..." comment. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
In article <7NudnY7T8YolBlDOnZ2dnUVZ5tSdnZ2d@giganews.com>, 
tim@seemywebsite.really says...
> > will look at AAs. Thanks, Tim. > > I do think the best way to get to 15V is from the 5V rail -- but each > individual circuit always ends up with its own quirks. > > I'm going to take the opportunity to voice a pet peeve here: > > <rant=on> > If you do use just two cells, make damned sure that you use a regulator > that's good down to 1.8V, or 2V at worst. NiMH and dry cells both are > good all the way down to 0.9V/cell: not working down that far is just > throwing away useful energy that could go to make your customer happy. > </rant> > > Have fun. > > >
I have a Fluke process DMM, that uses a 9V battery. from the day I got to the day I laid it to rest, when ever I used the current mode in it (24V out), I'd get ~ 10 mins of use and the DMM was dead. That's a nice design Fluke came out with, as useless as tits on a bull. Reminds me something SLOW_MAN would design, if he knew how. Jamie