Motherboard Forums


Reply
 
 
rickman
Guest
Posts: n/a
 
      11-28-2011, 09:47 PM
I am reading a CPU eval board data sheet that says it supports 1.8
volt interface for MMC cards. They don't seem to support SD cards.
Looking at wikipedia they say, "All SD card families initially use a
3.3-volt electrical interface. On command, SDHC and SDXC cards switch
to 1.8-volt operation." How is that intended to work? I don't see
the utility of requiring a voltage converter chip so you can first run
at 3.3 volts then switch to 1.8 volts. Is this the only way to make
this work if you don't want to have two types of cards? I guess I
would have expected the interface to work from what ever voltage is
present on the power pin, no?

So how is this used in a design typically? The CPU I am considering
can only work with 1.8 volt I/Os. Do I really have to use a level
shifter chip to complete this interface?

Rick
 
Reply With Quote
 
 
 
 
Leo Havm°ller
Guest
Posts: n/a
 
      11-29-2011, 04:23 AM
> I am reading a CPU eval board data sheet that says it supports 1.8
> volt interface for MMC cards. They don't seem to support SD cards.
> Looking at wikipedia they say, "All SD card families initially use a
> 3.3-volt electrical interface. On command, SDHC and SDXC cards switch
> to 1.8-volt operation." How is that intended to work?


Ask the manufacturer of the CPU eval board.

For HW design, just dump in a SN74AVC4T774 and be done with it.

Leo Havm°ller.

 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Re: lowsh Vio core voltages blah Abit 1 04-02-2004 07:09 PM
Voltages h2 Abit 4 03-03-2004 12:04 AM
NF7-S: can't monitor voltages/temperatures anymore! Wblane Abit 1 01-23-2004 05:21 AM
IS7 Question re: voltages noone@nowhere.com Abit 2 01-19-2004 10:48 PM
KV7 Voltages Trac Abit 2 12-01-2003 01:54 PM


All times are GMT. The time now is 01:48 AM.


Welcome!
Welcome to Motherboard Point
 

Advertisment