Buck Converter
Bucks and Boosts and Flybacks: There are many power electronic circuits used to convert from one DC voltage to another. Probably the most widely used is the simple "Buck" (or Step-Down) converter. A Buck transforms a higher voltage (and lower current) input into a lower voltage (and proportionally higher current) output. This design shows a typical automotive Buck application, where the battery input voltage (12.6V) is reduced to a regulated 5V output.
This design is "Live"" change any parameter (in blue) and run a simulation to see the results.
The simulation illustrates the Buck start-up transient. The design uses power stage component selections recommended in a Microchip WebSeminar*. The results of the simulation closely match not only the expected voltages and currents, but also the calculated component power dissipation levels. Efficiency is a key performance indicator for all modern power electronics.
This design includes a controller composed of ideal non-physical blocks, representing the compensation function, the PWM generator and MOSFET gate driver. These math-based control elements allow designers to verify the circuit's closed loop performance, before designing the actual implementation circuits.
Current conduction paths in the Buck Converter, On-state vs. Off-state
*Microchip WebSeminar: https://bit.ly/2XQCAS0
Because this is a live, interactive design, you can change the key parameters highlighted in blue. These include:
- The load resistance value (which changes the output load current)
- The output filter L and C values, as well as their parasitic resistances
- The MOSFET rds_on value
- The battery voltage
- The output target or set-point voltage, and the soft-start ramp time
- The PWM frequency
By changing these parameters and running new simulations, you will get a better understanding of their impact on the circuit's start-up performance and steady-state efficiency.