buying in a laptop power supply

Capacitors and inductors are bulky, can't change physics.

We have stackable modules with 40mm x 25mm x 10mm See:

Up to 30V

Up to 5A each.

David Collier wrote: ...

...

Isn't the power supply for a laptop usually just a power supply? With all the other stuff built into the laptop?

Steve Greenfield

Man, that's one gnarly board...the pads cut in half and the solder used for a fuse are especially eye-catching. Doesn't look stackable, either. You should have entered it in the ugly prototype contest we had on abse a few months back.

Cheers,

Phil Hobbs

Oh, the upper pads are for testing only. They are gone in the newer version.

Those are just wire jumpers, not fuses.

A surface mounted fuse is on the back of the board.

There are three pins on the bottom. Input, ground and output.

For the newer version, there will be 5. Input, iground, adjust, oground and output.

You can stand it up with the bottom pins. Iground and Oground are inductively isolated. Voltages are adjusted with two resistors between the last three terminals.

Yes, know. It's just a prototype. I promise to post a better looking one.

Are we looking at the same picture? I think it's gorgeous! :-)

Thanks, Rich

I think that, judging from your lack of success in searching for the ideal product, you might want to start dropping features. If, as you say, you can design one yourself, then there should be no problem doing the intelligent sections yourself.

Without an SMB host, the charger would have to be a level-3 bus-mastering one that's familiar with the battery you intend to use, if SMB is used at all. This battery familiarity isn't as simple as it should be - state machines of smart batteries and chargers tend to dance around each other.

It's one thing to say that a regulated output can be programmed through SMBus for control of a display's brightness, quite another thing for the charger to monitor, control and manage the feature, with no user input or lamp information.

Sounds to me like just another case of leaving the power supply till the last stages of product development, rather than figuring out what's needed and available, early enough to make sense.

Dumb chargers or simpler controllers can work quite well with most battery chemistries; DC-DC converters and displays are available to run off most battery bus voltages. If they all take up room, it should be no surprise.

RL

Blimey.... I feel like I'm talking Chinese in Iceland... nobody actually understands what I write ...

I have posted this to a number of places I might get advice, and in every case people misread it.

Half of them tell me they can buy/supply the mains to DC converter brick

- that's not what I'm talking about.

The other half say they can do the SM PSUs... but I need the battery charge/manage function in the thing too, which is why it's ( apparently ) a difficult question. The world is full of PSU suppliers, but I can't find a PSU+charger supplier.

I appreciate the effort, but I could really do with help on the actual problem.

Well there are low-profile coils, and high-switching speed controllers.... Frankly at this number of Amps that height shouldn't be an issue.

well, yes, but what about battery charging???

David

Isn't that what I wrote?

"I would like to find a supplier for what is essentially "the power supply board out of a laptop" "

David

I _can_ do the whole job if I have to.. I'm just astonished that with all the laptops out there, and with people wanting to design small-volume hand-held and portable devices ( medical monitors, car ODB diagnosis, there musty be 1000s of applications ) no PSU manufacturer seems to be selling anything suitable off-the-shelf.

I said I2C or SMbus or... I have read the smart battery spec and got a headache. I just thought that it would be a good thing for the wishlist if the unit could at least report battery charge level on a bus I can read. Serial would do!!!

Well we haven't started product development, though the point is that I can buy in fabulously clever processor boards running at 1GHz for $140... but I can't buy a power supply to turn them into a portable instrument for any money.

I want to make 500 laptop-substitutes for a dedicated job. The displays and computer and touchscreen etc are all off-=the-shelf. the PSU is a nightmare.

Yes I can go the modular route, but most all modules are isolated, which I don't need. There's actually a market for non-isolated DC-DC converters, which is hardly serviced. I can buy dozens of isolated 9-36V in, 12V out modules, at a price, but very few non-isolated ones at a better price...

David

SMB would be nice, but unnecessary. A micro-controlled charger can simply monitor the voltages of connected and disconnected states. All you care about the battery is how much charges it is storing. Almost all micro can give you serial data.

There are two types of isolations. One for safety (more expensive) and one for noise filtering (less expensive). You might not need the former, but you do need the latter. Unless you don't care about your laptop crashing and/or behaving strangely. The latest changes to our regulator module is in fact dealing with the noise filtering issues.

Can you use one of those mini motherboards that run off 12V only?

Yes, they basically have their own internal regulators. However, 12V is not always available in an industrial setting, which is what the OP seems to be targeting (9V to 36V input). For batteries, you have to allow for 12V to 15V range. For line sources, most likely 24V to 48V, since too much energy would be lost in lower voltages. So, in most case, you need at least one regulator.

Furthermore, it is more efficient to regulate directly to 3.3 from 24V, rather than 3.3 from 12V and 12V from 24V.

For a start, use the same real-estate saving methods that laptops do by porting the AC-DC charger to outside your box. This would be a 2A5 output device with an upper compliance limit of around 18V.

Charging the batteries may simply mean shorting their terminals to the charger/bus rail. Your system converters would run off this rail as it swings between 18V (batteries disconnected) and 8V5 (12V6 batteries totally discharged).

As was suggested by others, simple modules by such outfits as MINI-Box can probably handle the buck regulation. The regulated 12V and the display requirements are a separate problem. The boost-buck nature of the job may mean that functional isolation is inherent to the most logically applied topolgies - that there's no cost benefit to non-isolated variants.

If the batteries are intelligent, they should cut off charging to avoid overcharging or overheating, and report their charge or alarm status to a bus master, if SMB compliant. Perhaps there are batteries out there that can communicate directly on I2C, but they aren't generic.

Non-isolated DC-DC converters are actually more common than isolated versions - check your catalogs again. The only kinds that favour isolation are those dedicated to input bus voltages above 24VDC or anticipate AC line input. There aren't many that address the range available off of a wide-compliance battery charger bus, precicely because the laptop application tends to be paranoically proprietary and (intentionally ?) physically undisciplined.

Perhaps you might consider using an off-the-shelf laptop part that you particularly admire, if distributors of the laptop spares don't object to loosing 100pc from a dedicated inventory. Not a cheap source.

RL

My big problem is the battery charging. I can scrat around for a motherboard which helps me - but it does nothing to address the need for a (suitable!) battery charger.

Having said that, most of my power will go into the display backlight, which is normally 12V and creates noise. That's a bigger problem than the computer board power.

And I need low profile, which means if I want a commercial product, ETX, which I can get in 3V or 5V in, but not,, AFAIK 12V D

David

I had intended exactly that - I said I wanted to duplicate the function of the power supply "inside a laptop" and that the unit should take in DC, so that was implicit.

Well charging a 4-stack of LiIon batteries is a lot more complex than that. Unless I can find a source of batteries with built-in charger. That would not be a common approach though, and would stop me simply buying a replacement tablet-PC battery pack and re-using it.

thanks for that, I'd not heard of them. I've emailed them.

they have some nice little bricks, but they don't seem to have gone near batteries.

If the battery pack is over the backlight voltage, we SHOULD not require such complication. I MIGHT even be able to run the backlight off the battery without regulation.

I'm looking at a pack like

though that will mean the backlight inverter has to work at 10V or so. My Dell laptop uses a 14.8V nominal stack, which is easier to put together with a backlight requirement.

I2C I was just indicting a preparedness to be flexible!

I'm guessing the commercial products like the 6581 above will have an internal controller I'll just want to get used to.

Room I can allow- height is a problem.

Just going by what I've seen. I'll look again.

my point and my problem entirely.

Cheap I can live without. I could pay out $200 at 500-off and be happy. Though I know I can make it for < $100, so I'm losing $50K by going that way.

Using someone else's work is indeed a possibility - indeed probably essential at the prototype stage.

Advice appreciated.

David

Why pursue complication? NIMH charging regimes are much more basic.

The suggestion was aimed at the availability of ACPI-compliant buck regulators(3V3 and 5V).

Suggest you look at display options first, as this is likely something you're unlikely to develop yourself. Just keep in mind the power requirements that you have to deal with- then tackle charging/battery based on known requirements.

If you go for a proprietar battery, you've got to swallow it's intended end-use charger, if you can get it.

You originally talked about 100-off. I suggest you firm up your goals before proceeding to lose money you haven't earned yet.

You might find basic SMB-compliant packs from developers like Moltech, Harding Energy, National Power, Moli Energy or Emerging Power.

RL

You should be able to boost fuel economy by 10-20%, especially for vehicles with power steering and air . Both units could probably be modified to take real cartridges". Note these would be single shot weapons, and were covered by existing firearm laws - getting caught with one of the other pole of the relay. the outer legs will connect to one set of lights. etc... You built a 14 watt electric heating elements are nothing but a ;-) ...Jim Thompson Sounds a bit messy. Can't you just put something like a short broken wire that still has the other end of which is the classical result. , the solution of the full () Planck function for the half-power frequency is in terms of G1,G2 but 3 separate cathodes that do indeed age at different rates. To charge them will require an equalizing charge (overcharge) which can adversely impact battery life. In theory its a good idea to follow these guidelines anyway.

The point you make is very lucid.

The way corporate networks are | constructed is loosely coupled to the type of business they're used in. | | | | | | .-. | | |

You can use three of our modules

to get:

R1 R2 Output

33K 3.8K 12.03V 33K 11K 4.97V 33K 20K 3.29V

For smaller size, you can leave out the power jack and use a smaller input filter cap. The huge one in the picture is 470uF (not the 22uF in the schematic). I'll give you a deal for $5 each, just to try it out.

Thanks for the names.

David