Hi Leo,

Peter did that for educational purpose and it is fine at its place ,I dont think a discrete solution could fit my project as I have to deal with ESD also which comes ready built in 232 chips .If we use transistors I am not sure about issues like temperature stability and high baud rates 57Kbps? . But I have to look for more than a ready solution .
I saw the 232 datasheet and it states that the charge pump can deliever 2Vcc both phases ,so with 3.7V it is +/-7.4 Not Bad ! if we compare with +/-3V .It is given that the charge pump could accept voltages upto 5.5V but the lower side is left undocumented .But one thing is sure that according to standards it requires atleast -/+9V at the output . I know it will work with 3.7v battery but I have no gaurantee so as others have stated I must not use such a quick solution even if it works !

Regards
Sanjeev