[Gta04-owner] GSM / AT&T Access

Butrus Damaskus butrus.butrus at gmail.com
Fri Sep 2 19:59:53 CEST 2011


>> I'm not sure I got your question right.
>> Maybe you ment Monitoring and Injection?
>> Or using is for totally different purposes then GSM?
>> Then you will also have the problem of the dimensions of the circuits themself.
>>
>>> Also, would the USB OTG host chip be able to provide to full 500mA to power devices with?
>> I don't know BUT I wouldn't do that neither.
>> Imagine how fast you batteries would be drained this way.
>
> Exacty. There is a charge pump to convert the battery voltage to
> 5V as needed by USB. This has some less than 100% efficiency.
> So let's calculate: 5V at 500mA at 90% efficiency translates to
> 3.3V at 800mA. Well, the battery has 1200 mAh. So you could
> operate such a peripheral for less than 1 hour (the main
> system draws something between 200 and 600 mA if not
> in sleep).

But think about when you really, really need yout coffe ;-) :-P.


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