3 ms·

"It's totally possible to make it work, it just isn't terribly simple." Please, it's as simple as a three-component boost converter - one IC and two resistors.

"It's totally possible to make it work, it just isn't terribly simple." Please, it's as simple as a three-component boost converter - one IC and two resistors. Same thing I use to bump 1.2V up to 3.6Vto run LEDs. It takes zero space (7x7mm total.)

pfooti 10y ago
what's the efficiency of that boost converter? how much energy gets dissipated as heat in that setup, and is that likely to cause a fire?
- thesmok 10y ago
  Modern boost converters have efficiency from 80% to 95%. They also operate at high frequencies – 1MHz or even 3MHz, which allows to make inductors incredibly small. Boost converters aren't a problem for a long time now.
hwillis 10y ago
Sure. You could use an SOT23 or a QFN like this: http://www.digikey.com/product-detail/en/texas-instruments/TPS61090RSAR/296-15259-2-ND/566911 http://www.digikey.com/product-detail/en/texas-instruments/T... That's 4 mm x 4 mm (more with passives, but not too bad), and hits a solid 95% efficiency at the normal load of an iphone, and is above 90% all peak loads. Heat dissipation will be fine, all parts cost about $1.20. Low EMI. However, its still a dozen new components. It's a ~10% tradeoff somewhere and while that may be totally worth it, its not simple. Phones do not have square millimeters to spare.
- Arizhel 10y ago
  >Phones do not have square millimeters to spare. Actually, they do, when you're replacing the battery with one with 3 times the energy density. Use some of the saved space for your DC-DC converter.
  - hwillis 10y ago
    Its like... adding a turbocharger to a car. Yes, it is possible. There are even kits, after a fashion. But it is still not simple. Also, its not even at the stage of a hypothetical question yet. This battery would last about two weeks in an iphone under these load conditions. The only reason it "looks" possible is if you're considering a battery that is not this one.
dreamcompiler 10y ago
If it's a true boost converter, it's also going to need an inductor somewhere. If it's really just driving an LED, it could be a charge pump, which uses capacitors instead. But charge pumps probably can't handle the current level that a phone requires.
- lightedman 10y ago
  "If it's a true boost converter, it's also going to need an inductor somewhere." We use resistors as inductors. Plenty of wound resistors in teeny-tiny packages exist, that's how we have metal detectors with credit card-sized boards, the literal bulk of the unit is the frame and coil assembly and board housing + adjustment controls. Older gas charge pumps can handle it, but they're bulky and they are lossy and generate a lot of heat.

pfooti 10y ago

what's the efficiency of that boost converter? how much energy gets dissipated as heat in that setup, and is that likely to cause a fire?

thesmok 10y ago
Modern boost converters have efficiency from 80% to 95%. They also operate at high frequencies – 1MHz or even 3MHz, which allows to make inductors incredibly small. Boost converters aren't a problem for a long time now.

hwillis 10y ago

Sure. You could use an SOT23 or a QFN like this: http://www.digikey.com/product-detail/en/texas-instruments/TPS61090RSAR/296-15259-2-ND/566911 http://www.digikey.com/product-detail/en/texas-instruments/T... That's 4 mm x 4 mm (more with passives, but not too bad), and hits a solid 95% efficiency at the normal load of an iphone, and is above 90% all peak loads. Heat dissipation will be fine, all parts cost about $1.20. Low EMI. However, its still a dozen new components. It's a ~10% tradeoff somewhere and while that may be totally worth it, its not simple. Phones do not have square millimeters to spare.

Arizhel 10y ago
>Phones do not have square millimeters to spare. Actually, they do, when you're replacing the battery with one with 3 times the energy density. Use some of the saved space for your DC-DC converter.
- hwillis 10y ago
  Its like... adding a turbocharger to a car. Yes, it is possible. There are even kits, after a fashion. But it is still not simple. Also, its not even at the stage of a hypothetical question yet. This battery would last about two weeks in an iphone under these load conditions. The only reason it "looks" possible is if you're considering a battery that is not this one.

dreamcompiler 10y ago

If it's a true boost converter, it's also going to need an inductor somewhere. If it's really just driving an LED, it could be a charge pump, which uses capacitors instead. But charge pumps probably can't handle the current level that a phone requires.

lightedman 10y ago
"If it's a true boost converter, it's also going to need an inductor somewhere." We use resistors as inductors. Plenty of wound resistors in teeny-tiny packages exist, that's how we have metal detectors with credit card-sized boards, the literal bulk of the unit is the frame and coil assembly and board housing + adjustment controls. Older gas charge pumps can handle it, but they're bulky and they are lossy and generate a lot of heat.