We have a design using this device based on the web bench tool using 8-24V in, 24V out at 2.5A which recommends either a SEPIC or a boost with sync configuration. Our design uses the boost configuration, with the only changes being that the sync feature is not used, a 75.0K resistor is used instead on the FA pin , Cin is 220uF instead of 150uF, and we have a 10 ohm series resistor between Cin and Cbypass. We have shorted out the 10 ohm resistor with no apparent change in operation.
At no load we have an audible tick of about 10Hz and oscillation on the output of about 2V. As the load increases the frequency goes up as well. I have seen in another forum question (http://e2e.ti.com/support/power_management/non-isolated_dcdc/f/196/p/397488/1404554#1404554) that this issue is under investigation. If we drop the input voltage to 22.5V or lower the output is solid and quiet. We can also place a finger near the VIN pin and components and it goes solid and quiet as well. The referenced forum also recommends another part but that part is a 10 pin part. We are looking for a solution without having to change the existing circuit. If we use web bench for 23-25V in, 24V out at 2.5A we get only a SEPIC configuration recommended.
So the question is why do we have audible noise at 24V in. Should this work?
Here is the schematic, hopefully you can read it if not let me know.