The minimum time required for a signal from an input pin to propagate through combinational logic and appear at an external output pin.
In the Quartus® Prime Standard Edition software, you can specify the required minimum tPD for the entire project and/or for any input pin, output pin, or bidirectional pin. You can also assign a point-to-point minimum tPD assignment to specify the required delay between an input pin and a register, a register and a register, and a register and an output pin.