Hi all. I have searched the entire (it seems) internet, but can't seem to find what I'm looking for. I've found lots of chargers, and lots of power supplies, but not a combination.
I am creating a device (for me - not a school project) that has an 'acquisition unit' that measures a couple of temperatures and controls a fan. Using XBee radios, the data is sent to the 'control unit' that has an LCD display and a couple of buttons for control. The acquisition unit will be plugged into a power supply all the time, and the control unit will be battery powered and mobile.
My control board has a 3.3V power supply using an LM317. I am monitoring the input voltage using a voltage divider and an analog port on the MCU. When the supply voltage drops to a preset level, there will be a warning to plug in the power supply.
Here is the problem. I would like to use a 2S LiPo battery (7.4V) to have some overhead for the LM317. When I plug in the power supply (12VDC wall-wart), I want to charge the battery with a MCP73213 charge controller, while simultaneously providing 12VDC to the LM317.
The first image is one I found (I'm darned if I can find it again though):
My modification is this:
Sorry for my lousy drawing abilities. My question is this: Am I on the right track here? When the switch in the power jack transfers, am I going to get a power dropout? If so, is there a way to combat that?
Thanks for any help you can offer. I really appreciate it.
Andy
I am creating a device (for me - not a school project) that has an 'acquisition unit' that measures a couple of temperatures and controls a fan. Using XBee radios, the data is sent to the 'control unit' that has an LCD display and a couple of buttons for control. The acquisition unit will be plugged into a power supply all the time, and the control unit will be battery powered and mobile.
My control board has a 3.3V power supply using an LM317. I am monitoring the input voltage using a voltage divider and an analog port on the MCU. When the supply voltage drops to a preset level, there will be a warning to plug in the power supply.
Here is the problem. I would like to use a 2S LiPo battery (7.4V) to have some overhead for the LM317. When I plug in the power supply (12VDC wall-wart), I want to charge the battery with a MCP73213 charge controller, while simultaneously providing 12VDC to the LM317.
The first image is one I found (I'm darned if I can find it again though):
My modification is this:
Sorry for my lousy drawing abilities. My question is this: Am I on the right track here? When the switch in the power jack transfers, am I going to get a power dropout? If so, is there a way to combat that?
Thanks for any help you can offer. I really appreciate it.
Andy