I have 12V coming in to my board. It passes through a resistive divider and the voltage is dropped to 3.8V and this is the voltage required to power my device(can need up to max 2A from time to time). I want to add a li-poly battery and battery charger to this but I have a couple questions.

The charger i am using is the MAX8601. (http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4612)

When the 12V is connected, i want the charger to charge my battery, and provide 3.8V(after passing through resistive divider) to my device. When the 12V is removed, the battery(rated @ 3.8V) should then power the device.

V_IN -------------ResistiveDivider-3.8V---Device
| ..........................................................|
-----------------BatteryCharger---3.8-4.2V-
. ....................................................|
. ................................................Battery
(disregard all periods as they are just space holders)

I am trying to have it so the 3.8-4.2V is not applied at the same time as the voltage provided after passing through the resistive divider.

Thanks,
Pat

 

The IC you are using has a SYS output that will provide power to your load and will switch power sources automatically. However, I read in the data sheet that the maximum current is only 1 A so you should try and find an IC that will handle a larger current draw.

Most of these ICs have provisions to power the load already built in, you shouldn't have to do it yourself.