I'm designing a circuit that can be powered by either USB or a single NiMH cell. The NiMH will be boosted to 3.3V, and then an LDO will reduce both that and the USB 5V to 3.1V. I've attached a quick sketch.
As shown, the boost converter would need be able to resist backfeeding from the USB power. This is an example of a converter that I'm considering:
This converter has output overvoltage protection, short circuit protection, and output disconnect at shutdown. I've read the datasheet but I'm not entirely clear what the first two mean. Do they mean that I would be fine applying 5V to the output while the device is in operation? If so, would any current pass back through to the battery? Or, would I need to use the EN pin to shutdown the converter and disconnect the output when USB power is supplied?
Also, is the diode shown necessary?