| View previous topic :: View next topic |
| Author |
Message |
arrow
Joined: 17 May 2005
Posts: 213
|
| MMC/ SD Current Drawn upon Write? |
 Posted: Fri Jul 21, 2006 8:06 am |
 |
|
Hi
I was wondering if anyone could tell me what is the minimum current draw upon writting either to a MMC or SD cards?
I am planning to use Lithium 3V coin cell batteries and was wondering if these are powerful enough to do the write operation to MMC / SD?
Thank you in advance
a. |
|
 |
epideath
Joined: 07 Jun 2006
Posts: 47
|
|
| Posted: Fri Jul 21, 2006 9:00 am |
|
|
Well according to the datasheet the current draw max at 3.6V are:
READ - 50ma
WRITE - 60ma
SLEEP - 150uA
Regards |
|
|
arrow
Joined: 17 May 2005
Posts: 213
|
|
| Posted: Fri Jul 21, 2006 9:15 am |
|
|
Hi Epideath
Thank you- I am looking for these data sheets.
Can you please direct me to a link?
Regards
a. |
|
|
epideath
Joined: 07 Jun 2006
Posts: 47
|
|
|
arrow
Joined: 17 May 2005
Posts: 213
|
|
| Posted: Mon Jul 24, 2006 1:08 am |
|
|
Hi Epideath
Thank you very much! That is most helpful.
May I ask you before I start the development: I am going to try and
power my circuit with coin cell batteries (Lithium 2032).
I am wondering if these coin cells can be used to write (block write) to a MiniSanDisk card? and if so, for how long?
I was thinking of after every block write to have the card go to sleep. Thus if I have 4 block writes/second it would be a very small duty cycle, but is the coin cell battery powerful enough to do the writting?
Once again thank you- I appreciate it!
Regards
a. |
|
|
asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
|
|
| Posted: Mon Jul 24, 2006 4:47 am |
|
|
| arrow wrote: | | May I ask you before I start the development: I am going to try and power my circuit with coin cell batteries (Lithium 2032). |
Read the datasheet for the battery and get the battery capacity.
| Quote: | | I am wondering if these coin cells can be used to write (block write) to a MiniSanDisk card? and if so, for how long? |
You can capculate this from the write figures given to you and the battery capacity information.
| Quote: | | I was thinking of after every block write to have the card go to sleep. Thus if I have 4 block writes/second it would be a very small duty cycle, |
You will need to check the datasheet but from memory - it can take 500ms for the card to become active from powered down state. From idle state it takes about 5ms worst case. I do not remember how you put the card to sleep - I think it is just by keeping it inactive for a few milliseconds
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
|
|
|
FAQ 
Search
Register
Profile 
Log in to check your private messages 
Log in
