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MC34709 Li Cell Charger

Question asked by Mark Roy on Jun 9, 2014
Latest reply on Jun 10, 2014 by igorpadykov



I am using the MC34709 in a design.   We are using a 3.0V rechargeable lithium cell to backup the RTC on the MC34709.    I was wondering if there were any parameters or ratings on the charger circuit since it seems to be poorly documented in the datasheet.  The datasheet only lists the parameters of Table 19.   All of the values in this table are only "Typical" values and there are no minimums or maximums listed.    For example for safety reasons I would like to know what the maximum charge current is.    Also, is there any kind of reverse charge protection built in to the charger?


If a user accidentally installs the battery in reverse, what will happen?  Will this damage the MC34709?  Will it attempt to reverse charge the cell causing leakage or worse damage to the cell?

If there are no protections for reverse polarity then I may need to use a permanent battery instead to remove the possibility of user error.



Mark Roy