Hello.
I need some help with a simple circuit. Hope someone has some experience on the subject.
I need to make a small circuit with an RTC IC (eg. this http://pdf1.alldatasheet.com/datasheet-pdf/view/409913/MICROCHIP/MCP79411.html). The functions is that it has to log the time if the power fails for atleast a couple of days (it's sort of a tamper function/protection).
The RTC chip seems to be able to do that so I figure it would be smart to use a supercap to feed the IC in "powerfail-mode".
I have looked at this one: http://industrial.panasonic.com/www-data/pdf/ABC0000/ABC0000CE19.pdf
It seem to fulfill the needs (regarding case size, operating current/voltage).
My questions is:
1. In the datasheet the only voltage and current levels I can find is Maximum operating levels. I assume that is what the cap can deliver when not being charged(?). Then what about breakdown voltage and charge current?
2. Do I need to design a charging circuit for the cap?
Hope someone can help!
/O.
I need some help with a simple circuit. Hope someone has some experience on the subject.
I need to make a small circuit with an RTC IC (eg. this http://pdf1.alldatasheet.com/datasheet-pdf/view/409913/MICROCHIP/MCP79411.html). The functions is that it has to log the time if the power fails for atleast a couple of days (it's sort of a tamper function/protection).
The RTC chip seems to be able to do that so I figure it would be smart to use a supercap to feed the IC in "powerfail-mode".
I have looked at this one: http://industrial.panasonic.com/www-data/pdf/ABC0000/ABC0000CE19.pdf
It seem to fulfill the needs (regarding case size, operating current/voltage).
My questions is:
1. In the datasheet the only voltage and current levels I can find is Maximum operating levels. I assume that is what the cap can deliver when not being charged(?). Then what about breakdown voltage and charge current?
2. Do I need to design a charging circuit for the cap?
Hope someone can help!
/O.