Controlling ADC conversion of LTC2145-12

Dear Sir

I am desiging the circuits using  LTC2145-12 ADC. to avoid the noise conditins around ADC, I would like to start ad

conversion when input analog signal meets over the threshold level.

Data sheets saying that ENC clocking shall be done all the time , So AD conversion will not stop .

So How can I control the AD conversion like AD9826?