Capacitor charger with 24V input 40V output at 1A constant current

Hi, 

According to the datasheet, LT8391 is ideal for LED driver and battery charger applications. However, it did not specify applications related to capacitor or supercapacitor charging. Normally, you would need a precise control of charging current and voltage for supercapactior applications to prevent damage to the supercapacitor, controller, and input voltage source. You may need additional components along with the LT8391 such as an input current sense to prevent excessive overshoot of current during startup. I would suggest to use available off the shelf supercapacitor charger controllers like LTC3796 instead. You may refer to the link below for more details regarding supercapacitor chargers. Thank you. 

Supercapacitor Chargers | Analog Devices

LT3796/LT3796-1 - 100V Constant-Current and Constant-Voltage Controller with Dual Current Sense (analog.com)

LT Journal of Analog Innovation V22N2 - July 2012 - Combined Voltage and Current Control Loops Simplify LED Drivers, High Capacity Battery/Supercap Chargers & MPPT Solar Applications

Regards, 

Fritz