[Metalab Issues] #101: PowerZ-USB

[Metalab Issues]

#101: PowerZ-USB
------------------------+-------------------
Reporter:  anlumo       |     Owner:  anlumo
    Type:  enhancement  |    Status:  new
Priority:  minor        |  Keywords:
------------------------+-------------------
 Vierlex and myself are researching the possibility to create a new addon
 for the Metalab in addition to the PowerZ: A five-port USB 2.0 version of
 it that is compatible with iPhone, iPad and all other devices that don't
 use the USB charging standard.

 We looked into commercial solutions and were unable to find any that
 support more than one device (this could have been one:
 [http://www.kickstarter.com/projects/siminoff/pop-the-intersection-of-
 charging-and-design?ref=live POP], but the device was canceled due to
 issues with Apple).

 The iPad is the most demanding device for this application, and needs 1
 .5A-2A to charge, which means 10A in total. Thus, I propose the following
 power supply:

 * [http://at.rs-online.com/web/p/einbau-schaltnetzteile/7511572/ Emerson
 Network Power NPS62-M]

 It uses convection cooling (thus is silent), has <300mW no-load power
 consumption and has 80% efficiency. These properties were deemed very
 important and aren't available on cheaper parts (or PC power supplies).

 The iPad needs a specific setup of resistors to accept a charger for 2A
 charging:

 both need [http://at.rs-online.com/web/p/smd-widerstande/6792174/ 49.9kΩ]
 to GND and the following resistor to 5V:

 * D+: [http://at.rs-online.com/web/p/smd-widerstande/7217066/ 43kΩ]
 * D-: [http://at.rs-online.com/web/p/smd-widerstande/7217088/ 75kΩ]

 I'm not sure whether we're really capable of soldering a lot of 2mm SMD
 resistors… That's up for discussion.

 It would be cheaper to make multiples of these at the same time.

-- 
Ticket URL: <https://metalab.at/issues/ticket/101>
Metalab Issues <https://metalab.at/issues>
Metalab is a Hackerspace in Vienna's first district.