Does AD7616 requires an external reference clock?
The way I understand your question is that if the AD7616 needs external clock for its conversion process. The AD7616 is SAR ADC. The sampling and conversion clocking happen internally. There is no need for external clock but the AD7616 needs an SCLK for communicating with the microcontroller through SPI to read the converted data.
Thanks for your fast response.jcolao
What about a trigger?
What do you mean by trigger? If you mean here is how to start conversion. The AD7616 can start conversion through the CONVST pin. A low to high transition on CONVST initiates the conversion of the AD7616 on the selected Vin input. You can check details on the AD7616 datasheet in the Digital Interface section.