Prev: SD Card, miniSD Card, hot swap. 50k card detect, power switch..
Next: Wireless Home Phones?
From: whit3rd on 31 Mar 2010 14:48
On Mar 31, 10:04 am, Winfield Hill <Winfield_mem...(a)newsguy.com>
wrote:
>  With respect to SD Cards and miniSD Cards, as described
>  in the engineering documents at the SD Association's
>  website,http://www.sdcard.org/developers/tech/sd_apps/
>  and the OEM Product Manual, Version 2.2, June, 2007.
>  Document No. 80-36-00497
>
>  These cards have 50k pullup resistor on pin 1, which
>  they suggest you use for card detect, see page 24.
>
>  But they also suggest a MOSFET power switch, with a
>  delayed turn-on, page 26.  This is a hot swap issue,
>  since when the SD card is unpowered, you can't check
>  the 50k pullup to see if a card has been plugged in.
>
>  "Most card connectors have a card detect switch that
>  signals the SD host when the card is inserted....
>  I see there are up to three physical switches.
>  Hmm, then what's the 50k pullup for?

My Palm devices came with a plastic dummy (just a dust plug,
really) in the SD socket. It presumably hits the switches, but
doesn't have any pullup resistor. There are also
adapters (microSD to SD) that could fill the socket but needn't
contain a memory device.
 | 
Pages: 1
Prev: SD Card, miniSD Card, hot swap. 50k card detect, power switch..
Next: Wireless Home Phones?