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memory problem with micro max RM1

 
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memory problem with micro max RM1
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Tarquin
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Post memory problem with micro max RM1 Reply with quote
Hi Marko,

I have just started to put together the encoder and RDS part of my project and have a problem. The micro max ST-1 and micro max r-1 combination seem to work fine. but I am having a problem with rhe RM-1 holding data after power down even for the shortest re-cycle. There is 4.5v across the 0.22F cap which drops to 2v and rather quickly then to zero after after about 30sec loosing data. Have you seen this before?. 0.22F's are not easy to hand to try another.

cheers
Fri Sep 22, 2006 7:40 am View user's profile Send private message
pcs
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The only requirement for RM1 is that when you power down it takes about
1-2 seconds to save all data so you shouldn't power up again before this time
is over. Other than that you shouldn't have any problems.

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Marko - PCS Electronics
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Fri Sep 22, 2006 8:44 am View user's profile Send private message Visit poster's website
Tarquin
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Post Reply with quote
Marko,
Thanks for the prompt reply.
The problem is as I understand it, If I remove the 0.22F cap from the board and charge it up it holds the charge at 4.5v indefinitly.It has a natural leakage of 137uA. One would assume the memory back-up current would be below this as it has an estimated hold time of 10yrs.
From my measurements, whilst in circuit, after power down, the initial 4.5v drops rapidly thus data is lost. Can you take a measurement for me in your labs to see what you are getting across the cap after power down.
This isn't the 1-2 sec (save data) feature you advised me on.

cheers
Fri Sep 22, 2006 8:59 am View user's profile Send private message
pcs
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Post Reply with quote
You don't understand how the circuit works. This cap is not supposed to stay charged
more than about 2 seconds.

I can't tell you more

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Marko - PCS Electronics
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Fri Sep 22, 2006 9:30 am View user's profile Send private message Visit poster's website
Tarquin
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Post Reply with quote
Marko,

Are you suggesting that the circuit detects power off and uses the charge in the cap to write data to memory before the cap itself discharges taking around 1-2 seconds and not used to keep active a memory area drawring uA's for a number of years. Like a very mini UPS

cheers
Fri Sep 22, 2006 10:12 am View user's profile Send private message
pcs
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I can't tell you more

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Marko - PCS Electronics
--------------------------------------------------------
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Fri Sep 22, 2006 10:35 am View user's profile Send private message Visit poster's website
Tarquin
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Post Reply with quote
Marko,

I think I may have found the answer. I have a very good precision power supply and have taken to turning it on/off from its mains input rather than from DC out. Even whilst 4amps are been drawn from it, it can take 6-7 sec before the voltage slowly decays.I can only assume the RM-1 needs to see a sudden loss in power for it to do its (back-up) as if I remove the DC via switch it works ok but reducing the DC slowly to it, it doesn't save data.
This info might be useful to someone.

cheers
Fri Sep 22, 2006 2:47 pm View user's profile Send private message
pcs
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Yep, that might be it.

When powering down use a switch and there will be no problems.

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Marko - PCS Electronics
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Fri Sep 22, 2006 3:51 pm View user's profile Send private message Visit poster's website
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