Had read somewhere not to connect two power sources at the same time to the MCU, as I want to have a Serial Connection power source and a battery backup. Even though I think it is ok with Whisper node, just want to confirm.
https://bitbucket.org/talk2/whisper-nod ... ttery-vbat
Battery: VBAT
The Battery input is directly connected to the MCP16251 step-up regulator. To be as efficient as possible there's no diode or protection on this line, do not reverse the polarity. The VBAT can be powered via the micro connector Molex Picoblade or from any PCB VBAT Pad - check the board pinout for details.
Although the board has been tested and able to run down to 0.75V, the recommended/start voltage must be between 0.9V and 3.3V.
*Note: Depending on the current requirement, the VBAT minimum voltage might need to be above 0.9V - see MCP16251 datasheet.
Power Supply: VIN
The VIN is connected to the LDO MCP1700. The supplied voltage must be between 3.4V and 6V. The VIN can be powered via the Micro USB connector or from any PCB VIN Pad - check the board pinout for details.
By-Passing the Regulators
An alternative way to power the board is supplying 3.3V directly to one of the 3V3R1 pins. Note by doing that you'll be by-passing any kind of built-in regulation, so make sure the power source is stable or it might cause permanent damage to the board.
Power Backup
It's important to highlight that the VIN will take precedence over VBAT, if it's over 3.4V. In other words, once a power supply is connected to VIN, it'll disable the step-up regulator by pulling its enable pin low. In this configuration the battery consumption will be as low as 3uA.
In case the power supply is disconnected, or it stop working, the step-up regulator will be re-enabled and will start feeding 3.3V to the 3V3R1.
Battery: VBAT
The Battery input is directly connected to the MCP16251 step-up regulator. To be as efficient as possible there's no diode or protection on this line, do not reverse the polarity. The VBAT can be powered via the micro connector Molex Picoblade or from any PCB VBAT Pad - check the board pinout for details.
Although the board has been tested and able to run down to 0.75V, the recommended/start voltage must be between 0.9V and 3.3V.
*Note: Depending on the current requirement, the VBAT minimum voltage might need to be above 0.9V - see MCP16251 datasheet.
Power Supply: VIN
The VIN is connected to the LDO MCP1700. The supplied voltage must be between 3.4V and 6V. The VIN can be powered via the Micro USB connector or from any PCB VIN Pad - check the board pinout for details.
By-Passing the Regulators
An alternative way to power the board is supplying 3.3V directly to one of the 3V3R1 pins. Note by doing that you'll be by-passing any kind of built-in regulation, so make sure the power source is stable or it might cause permanent damage to the board.
Power Backup
It's important to highlight that the VIN will take precedence over VBAT, if it's over 3.4V. In other words, once a power supply is connected to VIN, it'll disable the step-up regulator by pulling its enable pin low. In this configuration the battery consumption will be as low as 3uA.
In case the power supply is disconnected, or it stop working, the step-up regulator will be re-enabled and will start feeding 3.3V to the 3V3R1.