We'll use two LTM4622 or one LTM4644 to generate four different voltage.
One of this voltage is 5V. What's the minimun Vin Value to have Vout = 5V?
Is there a equation to calculate this Vin minimum value?
You can derive it using the minimum off time of the controller, the switching frequency, and the duty ratio. However, it also depends on a lot of factors such us the output current, the ambient temperature, the power losses, etc.. Kindly refer to LTPowerCAD tool as it will give you the minimum input voltage according to your application. It should raise a flag if you input a voltage lower than required minimum input voltage. Thank you.