Power from USB & DC Adapter (was Re: Design Files/Gerbers of SAKC V2)

David Reyes Samblas Martinez david at tuxbrain.com
Fri Jul 30 11:49:46 EDT 2010


2010/7/30 Carlos Camargo <cicamargoba at gmail.com>:

> Arduino for example, works with 5V,
Wrong, the most common board "duemilanove":
from his specification page[1]
Operating Voltage	5V
Input Voltage (recommended)	7-12V
Input Voltage (limits)	6-20V

it only use 5V as input when powered though USB,

I you have a 5V power source you can use the USB plug to avoid the 6V
input limitation on Vin,


> I think that the daughter card will have the specific power supply, so we
> can reduce the SAKC complexity and maintain the flexibility.
ok I can agree in fact "low" voltage from higher to 5V is no a big
deal, a voltage regulator before the plug can fit for an especific
aplication. rising voltage is allways more complicated.
>
>
> Carlos
>
>
>
> On Fri, Jul 30, 2010 at 10:17 AM, David Reyes Samblas Martinez
> <david at tuxbrain.com> wrote:
>>
>> I must agree with Ron that we don't have to save in "poka yokes" on
>> the power sourcing on SACK
>> +1 to the  +/- protection
>> +1 to the +5V collide protection
>>
>> and how much cost and space is for the power regulator?
>>
>> 2010/7/30 Ron K. Jeffries <rjeffries at gmail.com>:
>> > Please make sure that the design protects
>> > against plus and minus being plugged in wrong.
>> > I think that implies a zener diode.
>> > the extra cost of a 5V supply that accepts a fairly
>> > wide range of input voltage say 12v or less
>> > is probably worth it IMO
>> > SAKC is prolly less price sensitive than Nanonote.
>> > ---
>> > Ron K. Jeffries
>> > http://ronkjeffries.posterous.com
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > On Fri, Jul 30, 2010 at 07:44, Carlos Camargo <cicamargoba at gmail.com>
>> > wrote:
>> >>
>> >> Hi Adam
>> >>
>> >>
>> >>
>> >> On Fri, Jul 30, 2010 at 8:53 AM, Adam Wang <adam at sharism.cc> wrote:
>> >>>
>> >>> Hi,
>> >>>
>> >>> 1, I made a mistake on D10 footprint confirmation, It must be 0805 to
>> >>> meet MSCD104H. Pls change this to 0805 package.
>> >>
>> >> ok, I'll fix it
>> >>
>> >>
>> >>>
>> >>> 2, maybe mark a concentric circles with central ring to mark "+" and
>> >>> outer ring marked a "-" nearby DC Jack to suffer from mistakes by
>> >>> novices.
>> >>
>> >> Agree
>> >>
>> >>>
>> >>> 3, last but not least, current design of SAKC V2 have a condition that
>> >>> is
>> >>> it can not use +5V power at the same time either from USB cable
>> >>> (0.5A) or DC
>> >>> adapter(can be more). If using DC adapter fixed +5V in already,
>> >>> you must _remember_ to take out mini-jumper on J18 first, then plug-in
>> >>> usb
>> >>> cable to do s/w work. If you forgot that take out mini-jumper, after
>> >>> plugging usb cable; There must be have power +5V "collide" together.
>> >>> This
>> >>> UNSAFE condition will be happened once mindless to forget to take out
>> >>> mini-jumper. And possibly let USB host device to be have damage or
>> >>> even DC
>> >>> adapter source. Also if remove DC adapter, the SAKC it can only get
>> >>> 0.5A
>> >>> from usb, unworthy a bit. so
>> >>>
>> >>> 1) remove the DC adapter reducing the hardware hacking usability of
>> >>> the
>> >>> board a lot.
>> >>
>> >>
>> >>>
>> >>> 2) remove USB power, adding the need for an extra power adapter for
>> >>> every
>> >>> user.
>> >>
>> >>
>> >>>
>> >>> 3) add additional circuitry to make both USB & DC power stable in all
>> >>> cases. User should have the chance to update s/w from USB while still
>> >>> some
>> >>> h/w parts connected to SAKC board's extendable 40pins header to get
>> >>> 3.3V
>> >>> supply( actually comes from 5V) to outside application.
>> >>
>> >> Yes, I'm trying to solve this issue, I think that we can use a single
>> >> circuit Power On Reset + Transistor:
>> >>                             TRANSISTOR
>> >> USB_VCC-------------|S|           |D|----------- 5V
>> >>                                                        |
>> >>                                      |G|              |
>> >>                                        |               |
>> >> DC_WALL------|  POR |----------------------
>> >>
>> >>
>> >> When DC_WALL = 0V  Transistor is ON so 5V = USB_VCC
>> >> when DC_WALL >= POR's threshold => Transistor is OFF =>  5V = DC_WALL
>> >>
>> >>>
>> >>> Also if SAKC comes with capability of having strong wide power range
>> >>> input, this can make/let additional circuities connected to SAKC
>> >>> easiler and
>> >>> more flexible with ONLY one DC adapter. Fg. real ROBOT industries
>> >>> works
>> >>> around +12V or +9V supply. IMO if this can be true. SAKC will be more
>> >>> stronger. Surely aside from cost evaluation.
>> >>
>> >> We can't provide all the possible voltages for all the possible
>> >> applications. We can add an additional 5v regulator with a wide input
>> >> range,
>> >> but this increase the cost & the size.
>> >> Carlos
>> >>
>> >>
>> >> --
>> >> Carlos Iván Camargo Bareño
>> >> Profesor Asistente
>> >> Departamento de Ingeniería Eléctrica y Electrónica
>> >> Universidad Nacional de Colombia
>> >> cicamargoba at unal.edu.co
>> >>
>> >> _______________________________________________
>> >> Qi Developer Mailing List
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>> >
>> >
>> > _______________________________________________
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>>
>>
>>
>> --
>> David Reyes Samblas Martinez
>> http://www.tuxbrain.com
>> Open ultraportable & embedded solutions
>> Ben NanoNote, Arduino, Openmoko
>> Hey, watch out!!! There's a linux in your pocket!!!
>>
>> _______________________________________________
>> Qi Developer Mailing List
>> Mail to list (members only): developer at lists.qi-hardware.com
>> Subscribe or Unsubscribe:
>> http://en.qi-hardware.com/mailman/listinfo/developer
>
>
>
> --
> Carlos Iván Camargo Bareño
> Profesor Asistente
> Departamento de Ingeniería Eléctrica y Electrónica
> Universidad Nacional de Colombia
> cicamargoba at unal.edu.co
>
> _______________________________________________
> Qi Developer Mailing List
> Mail to list (members only): developer at lists.qi-hardware.com
> Subscribe or Unsubscribe:
> http://en.qi-hardware.com/mailman/listinfo/developer
>



-- 
David Reyes Samblas Martinez
http://www.tuxbrain.com
Open ultraportable & embedded solutions
Ben NanoNote, Arduino, Openmoko
Hey, watch out!!! There's a linux in your pocket!!!




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