I have a battery powered board in which the normal power mode is a 3.6V Li ion battery through a TPS72728 LDO providing 2.8V attached to the DVCC and AVCC power pins. The product has the ability to be stored with the LDO turned off so that minimal current is drawn. When we need to use the product it is plugged into USB and we use the USB LDO in the MSP430F5528 to provide the power to DVCC and AVCC to start the application. I have a diode in series with VUSB to protect the USB LDO. While in USB mode the 2.8V LDO is turned on.
My question is are there any issues with overdriving the voltage on the 2.8V LDO from the USB LDO? It is working with the current design I have but I want to make sure that this will work across the range of USB LDO voltages which goes up to 3.6V. I am currently seeing 3.3V at the output of the LDO with a drop across my diode down to 2.9V.
Thanks,
Gary Parrett