http://www.ti.com/lit/ds/symlink/tps61253.pdfThe datasheet for this regulator mentions "reverse current protection" in regards to the shutdown mode, but it does not mention reverse voltage protection in general.
For example on page 16 it states:
Pulling the EN and BP pins low forces the device in shutdown, with a shutdown current of typically 1 ?A. In this
mode, true load disconnect between the battery and load prevents current flow from VIN to VOUT, as well as
reverse flow from VOUT to VIN.
And on page 17 it says:
9.3.3 Load Disconnect and Reverse Current Protection
Regular boost converters do not disconnect the load from the input supply and therefore a connected battery will
be discharged during shutdown. The advantage of TPS6125x is that this converter disconnects the output from
the input of the power supply when it is disabled (so called true shutdown mode). In case of a connected battery
it prevents it from being discharged during shutdown of the converter.
However if you look at the block diagram on page 15, there is a PFET between VOUT and SW, and no direct connection between VIN and VOUT aside from the inductor between VIN and SW. And the PFET is oriented such that the body diode, which is not pictured for whatever reason, should have the negative side pointed towards VOUT. So in theory, if I have 5V on VOUT from a USB port, it should not be able to flow back into my battery even if the battery is too dead for the regulator to output 5V, right?