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Old 03-16-2013, 02:27 PM   #21
Ken Maltby
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Posts: 4,466
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Join Date: Dec 2009
Location: The Heart of Texas
Device: Boox Note2, AuraHD, PDA,
Quote:
Originally Posted by HarryT View Post
No, that's not what I was referring to. I meant that whenever an SD card is inserted into your reader, it will draw a (very) small account of power from the device, even when not actually being accessed; this is called the "standby current". It's a tiny amount, but it's not zero. A typical standby current would be about 0.2mA, compared to perhaps 80-100mA when the card is being accessed.
I would have to admit that any device needs to have a means to detect
that an SD card or other storage media is connected, a constant current
applied to a pair of pins in the interface could be one means used, but it
would be a poor device that required any appreciable power draw from the
battery. For any practical purpose, including any effect on the time provided
by a charge, there would be no effect what so ever.

Luck;
Ken
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