I am sorry to mislead.....I see that I erred in my comments about the Sipex SP3223 part. The voltage conversion circuit in this part is only a doubler! The data sheet here... http://www.sipex.com/products/pdf/SP3223_3243.pdf ...does indeed specify only a "doubler" configuration that produces driver output swings of about +/- 5.5 volts. It also declares that the chip is compatible with RS232-F where signals of some 5 volts are acceptable.

Michael Karas