Hello,
I'm developing a project where the main input source is a 3V Lithium coin battery like this:
https://www.digikey.com/product-detail/en/panasonic-bsg/CR2032/P189-ND/31939
So I used a TPS61222 because I need a fixed 5V output to power a circuit with ATmega328/Arduino.
However, the design will also support an external 5V voltage source. For this, I thought of using a schottky diode, from the external 5V to the internal 5V generated by the TPS61222, as shown in the figure below:
I did this to ensure that the internal 5v source does not conduct current to the external 5V source.
By observing the functional block diagram of the datasheet of the TPS6122x, I see that the MOSFET at the VOUT output has a diode that protects against current in the opposite direction. In this way, I decided not to put a schottky diode, from the internal 5V source to the external 5V source. Because I also do not want a voltage drop at the internal 5V source output.
My project has to be low cost, so I did not choose to use automatic selection circuit like those of the Arduino Uno board, nor have I own ICs for automatic selection of sources like some LTCs that I've been researching.
My question is: how am I implementing the circuit, do I have any risk of damaging the TPS61222 when the two power supplies are turned on simultaneously?
PS.: English by google translator!
