I have designed a SEPIC converter out of your datasheet, page 25, with an input span from 4.5-30 volt and the output at 25 volt will be used to charge a capacitor of 14mF.
When I put on the voltage, testing with 12 v to 30v, at the input the output voltage will rise very slowly but it never reaches the level of the input voltage.
If i disconnect the 14mF capacitor and don't have any load at the output the output will immediately go to 25 volt.
If I disconnect the 14mF capacitor but place a resistor of 100 ohm over the output from the converter to GND the converter will not start at all.
Can you please give me any suggestions how to solve the problem.