Selecting the right control strategy for a fixed frequency buck regulator


A fixed frequency buck generator is a circuit that provides a controlled, stepped-down DC voltage supply at the output, and it can be used for a number of applications. It uses inductors and capacitors to help maintain a voltage level, and a set of high speed switches to time the charging and discharging of the components. There are two ways to control the fixed frequency buck regulator, each having their own set of advantages and disadvantages.


One way is to control it by controlling the output voltage of the control circuit. Voltage mode control is less susceptible to noise and has a single feedback loop. It is also easier to regulate the load, but it needs a high bandwidth error amplifier and it is tricky to control light load efficiency. Another method of controlling a fixed frequency buck regulator is to use the current mode control. It has an inherent feed forward element that improves line transient performance, but it introduces sub-harmonic oscillations in the circuit without slope compensation.


The choice of control strategy for this unit depends upon the load requirements. Make sure that you consider the critical operational elements in the load and choose the control technique accordingly.