New article: Power Delivery in a Modern Processor

Article: Power Delivery in a Modern Processor
By: Rob Thorpe (rt.delete@this.nowhere.com), May 15, 2020 6:36 pm
Room: Moderated Discussions
Travis Downs (travis.downs.delete@this.gmail.com) on May 13, 2020 3:07 pm wrote:
> Danjel McGougan (danjel.delete@this.mcgougan.se) on May 13, 2020 6:52 am wrote:
> > David Kanter (dkanter.delete@this.realworldtech.com) on May 11, 2020 7:37 am wrote:
> > > Friends, posters, and lurkers,
> > >
> > > Power delivery is one of the most significant challenges in modern processors. The power
> > > delivery network (PDN) must meet the demanding requirements of modern CMOS technology,
> > > supply power with excellent efficiency, and swiftly respond to changes in power draw.
> > >
> > > I just published a new post that goes into detail on power
> > > delivery: https://www.realworldtech.com/power-delivery/
> > >
> > > It includes a brief discussion of system level power delivery, Intel's FIVR, and decoupling capacitors.
> > >
> > > As always, please take a look and comments/feedback/questions welcome here!
> > >
> > > David
> > >
> >
> > Thank you for a great article!
> >
> > Just a minor nitpick:
> >
> > You mention lithium-ion batteries in laptops on page 2 and say that they output 3.7V DC.
> > While it is true that an individual cell nominally outputs 3.7V, the battery pack of a
> > typical laptop have multiple cells in series delivering a higher voltage. Typically there
> > are 3 or 4 cells in series delivering ~11V or ~15V nominally from the battery pack.
> >
>
> Yup, and I guess that's why power bricks for laptops usually output 15V - 20V: so they can
> use the same step-down DC-DC converter for both wall and battery input. The similar voltage
> range means that you could efficiently use a single converter optimized for that range.
>
> Or maybe 15-20V is just a convenient voltage on the safety vs power-loss tradeoff curve.

The other reason is charging the battery pack itself.

The cable from the charger to the laptop is quite long. You don't really want to run ~3.7V though it at lots-and-lots of amps. It would be very inefficient. So, that link has to be a fairly high voltage.

Once you've done that you really want the battery pack at around the same voltage, at least just below. That way it can be charged from the cable. If the battery pack used a much lower voltage then you'd need *another* DC-DC converter for that. That's because everyone expects to be able to use their laptop while the battery is charging.

< Previous Post in ThreadNext Post in Thread >
TopicPosted ByDate
New article: Power Delivery in a Modern ProcessorDavid Kanter2020/05/11 07:37 AM
  New article: Power Delivery in a Modern ProcessorMaynard Handley2020/05/11 10:03 AM
    Buried power rails, super vias, etc.David Kanter2020/05/11 11:44 AM
      Buried power rails, super vias, etc.Maynard Handley2020/05/11 06:06 PM
  InductorsMoritz2020/05/11 12:01 PM
    InductorsDavid Kanter2020/05/11 12:36 PM
  New article: Power Delivery in a Modern ProcessorTravis Downs2020/05/12 07:53 AM
    New article: Power Delivery in a Modern ProcessorJason Creighton2020/05/12 09:15 AM
      New article: Power Delivery in a Modern ProcessorDan Fay2020/05/12 09:35 AM
        New article: Power Delivery in a Modern ProcessorJason Creighton2020/05/13 09:09 AM
          New article: Power Delivery in a Modern ProcessorRicardo B2020/05/13 11:47 PM
            New article: Power Delivery in a Modern ProcessorMichael S2020/05/14 12:29 PM
              New article: Power Delivery in a Modern Processoranon³2020/05/14 05:22 PM
              New article: Power Delivery in a Modern ProcessorRicardo B2020/05/15 05:06 AM
                New article: Power Delivery in a Modern ProcessorMichael S2020/05/15 05:13 AM
      New article: Power Delivery in a Modern ProcessorTravis Downs2020/05/13 03:01 PM
    LDO power savingDavid Kanter2020/05/12 10:16 AM
      LDO power savingYoav2020/05/13 03:56 AM
        LDO power savingTravis Downs2020/05/13 06:44 AM
          LDO power savingDan Fay2020/05/13 07:03 AM
            LDO power savingTravis Downs2020/05/13 03:02 PM
              LDO power savingRicardo B2020/05/14 12:08 AM
    Asynchronous CPU?dmcq2020/05/12 01:05 PM
      Hindered by device testing and design validationPaul A. Clayton2020/05/12 02:13 PM
        Hindered by device testing and design validationMark Roulo2020/05/13 08:22 AM
          Hindered by device testing and design validationAnon32020/05/14 07:06 AM
  Work scheduling for moderating powerPaul A. Clayton2020/05/12 10:15 AM
    Work scheduling for moderating powerDavid Kanter2020/05/12 10:40 AM
      Work scheduling for moderating powerPaul A. Clayton2020/05/14 09:27 AM
    Work scheduling for moderating powerTravis Downs2020/05/12 01:25 PM
      That is certain one real world example (NT)Paul A. Clayton2020/05/14 09:28 AM
  New article: Power Delivery in a Modern ProcessorDanjel McGougan2020/05/13 06:52 AM
    New article: Power Delivery in a Modern ProcessorTravis Downs2020/05/13 03:07 PM
      New article: Power Delivery in a Modern ProcessorRob Thorpe2020/05/15 06:36 PM
        New article: Power Delivery in a Modern ProcessorRicardo B2020/05/15 10:31 PM
  Bypassing capacitors & testingRob Thorpe2020/05/15 06:54 PM
  New article: Power Delivery in a Modern ProcessorRicardo B2020/05/15 10:22 PM
    New article: Power Delivery in a Modern ProcessorDavid Kanter2020/05/16 09:03 AM
Reply to this Topic
Name:
Email:
Topic:
Body: No Text
How do you spell purple?