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Joined: 17 May 2005
Posts: 213
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| MMC/ SD Current Drawn upon Write? |
 Posted: Fri Jul 21, 2006 8:06 am |
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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. |
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epideath
Joined: 07 Jun 2006
Posts: 47
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| Posted: Fri Jul 21, 2006 9:00 am |
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Well according to the datasheet the current draw max at 3.6V are:
READ - 50ma
WRITE - 60ma
SLEEP - 150uA
Regards |
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Joined: 17 May 2005
Posts: 213
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| Posted: Fri Jul 21, 2006 9:15 am |
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Hi Epideath
Thank you- I am looking for these data sheets.
Can you please direct me to a link?
Regards
a. |
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epideath
Joined: 07 Jun 2006
Posts: 47
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Joined: 17 May 2005
Posts: 213
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| Posted: Mon Jul 24, 2006 1:08 am |
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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. |
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asmallri
Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia
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| Posted: Mon Jul 24, 2006 4:47 am |
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| 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!! |
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