What will happen having only a DC source and a diode connected in reverse?
Will the diode or the source overheat over time or something bad might happen if you let it operate like that?
Electronic – A DC source and only a Reverse Diode
diodesreverse-polarity
Related Solutions
There are different SPICE parameters..
For example, the NXP model has TT = 3.48E-9
Central Semiconductor has TT = 2.88E-9
Vishay 1N4148W (T154D chip) has TT = 4E-9
None of those looks much like 20ns, but I didn't look at every maker of 1N4148s.
In any case, you may find this Matlab page useful.
Datasheets do not typically provide values for TT and τ. Therefore the Diode block provides an alternative parameterization in terms of Peak reverse current, Irrm and Reverse recovery time, trr. Equivalent values for TT and τ are calculated from these values, plus information on the initial forward current and rate of change of current used in the test circuit when measuring Irrm and trr.
Here's the relevant part of the system diagram from the datasheet you linked:
A Schottky diode typically has a forward voltage drop of 0.2 to 0.3 V. So if 5 V is applied at "V+", then only about 4.8 V is available to supply the Richtek switching converter or any other circuits that might be connected to that same circuit node.
The reason it's called a "reverse polarity protection" diode is because its function is to protect the circuit in case the USB connector is somehow connected in reverse, applying ground to the "V+" node and +5 V to the ground node of the circuit. In that case the diode will be reverse biased and not allow current to flow through the circuit.
Best Answer
You're about 1/5th the way from the center on the left of the graph. You'll get a marginal reverse current, but it's so little it wouldn't matter to much electronics. Your battery would drain ever so slowly. Internal battery drain current would probably be higher. So basically your circuit does nothing.