Hi,
We are building a charger for Li ion battery using
the LP3947 IC from national semiconducor.
Presently i have read the application notes from its
datasheet but still i have the following doubts in
general -
1.how can i use a controller (atmega 8 in my case) to
make lp3947 switch from one mode to anther For eg
-in the datasheet it is written that "As soon as pack
terminal reaches 4.2V (or 4.1V), the controller starts
operating in constant voltage mode ".What i mean
to say is how would i source different currents to the
battery (during the different stages of
charging).Have i to build seperate circuits
supplying different ranges of currrent and control
them through the controller.OR something else
needs to be done
2.In the flowchart given in the datasheet it compares
the voltage at the Ts pin to monitor battery
temperature.But a microcontroller understands only
two logic levels so how can i compare a voltage at a
pin to lie within a particular range.(as in this case
the voltage at Ts pin should lie between 1.39 and
2.42 volts).
as it would be clear basically i have a problem how to interface the microcontroller with LP3947 to control its various stages of operation and monitor the battery temperature.
These questions may sound stupid but still i hope
someone would try n clear my doubts
regards
atul
We are building a charger for Li ion battery using
the LP3947 IC from national semiconducor.
Presently i have read the application notes from its
datasheet but still i have the following doubts in
general -
1.how can i use a controller (atmega 8 in my case) to
make lp3947 switch from one mode to anther For eg
-in the datasheet it is written that "As soon as pack
terminal reaches 4.2V (or 4.1V), the controller starts
operating in constant voltage mode ".What i mean
to say is how would i source different currents to the
battery (during the different stages of
charging).Have i to build seperate circuits
supplying different ranges of currrent and control
them through the controller.OR something else
needs to be done
2.In the flowchart given in the datasheet it compares
the voltage at the Ts pin to monitor battery
temperature.But a microcontroller understands only
two logic levels so how can i compare a voltage at a
pin to lie within a particular range.(as in this case
the voltage at Ts pin should lie between 1.39 and
2.42 volts).
as it would be clear basically i have a problem how to interface the microcontroller with LP3947 to control its various stages of operation and monitor the battery temperature.
These questions may sound stupid but still i hope
someone would try n clear my doubts
regards
atul