1) What is the difference between ST232A and ST202? The pin out and all data seems to be identical, but ST202 seems to be slightly cheaper. 2) Is it possible to use only the switch capacitor inverter, but not the voltage doubler?

[CKans.1]

I want to utilize the very low power supply current of typical 1.5 mA to make a galvanic separated RS-232 interface, which is driven by RTS and DTR (trough two diodes) on the RS-232 side. The plan is to connect the cathodes of the two diodes to V+ and then let the inverter generate V-. Vcc for the ST202/232A and the RS-232 side of the digital isolator is then driven by a 5V LDO regulator (or switch mode supply) from the same point. This is much more efficient than using the voltage doubler to generate V+ as the output current drawn from Vcc is then doubled, which will cause a much higher power loss in the LDO.