Guck mal bei maxim:

http://para.maxim-ic.com/results.mvp?q=rs232&r=0&an_1=Family&av_1=RS-232%20Line%20Driver%2FReceivers&mh_1=1&wt_1=0&an_2 =Supply%20Voltage%20(V)&av_2=3.3&op_2=in&an_4=Numb er%20of%20Tx&av_4=1&op_4=ge&an_5=Number%20of%20Rx& av_5=1&op_5=ge&an_8=Int.%20Chrg.%20Pump&av_8=Yes&t ree=master&p=1