Point of load (POL) is the most common low voltage DC-DC application, it is basically a step down voltage converter. The output voltage, Vout is lower than input voltage, Vin. Take the computer as an example, the main reason for having POL is to meet different load voltage requirements. For example, CPU requires 1 V on average, USB port requires 5 V, DDR3 memory requires 1.5 V. Normally users will have multiple POL circuits on the board. Given a fixed input voltage, what defines the Vout is the duty cycle ratio. Duty cycle is calculated as the high side switch on time over the entire switching period (which includes high side and low side on time as well as dead time). Vout is therefore, the multiplication result of Vin and duty cycle. To convert a 10 V input to 5 V output, the duty cycle is 50%, therefore, the high side switch on time needs to be 50% of the entire switching period.