Bootstrap Capacitor Calculation Help

Hi

I am currently learning how to calculate the bootstrap capacitor for IR2110 Application. So far I have identified every parameters apart from one:

Qgate 27E-06
Frequency 21600
Icbs(leak) 0
Qls 5.00E-09
Vcc 14
Vf 0.78
Vls 4.5
Iqbs(max) 230E-06
Vmin ??

I use the forumla from Application Note AN-978 on page 6. At the moment I am not certain on how to obtain Vmin, I use a half bridge configuration and the voltage is about 100V and the IGBT is IRG4BC20UD.

Please explain me how to obtain Vmin?

Regards

MM