TDC1000: transmitter pin issue

Part Number:TDC1000

HI,

     i am working on water flow meter so am using 1Mhz transducer Audio-well Transducer,This Transducer needs 3V to 5V peak to peak voltage but am getting only 750mV at the TX pin of TDC-1000. what would be the problem or how can i boost voltage level in TDC1000 TXpin.