Multiphase Buck Converters

Switched mode DC-DC converters, including switching regulators, switching controllers, and PMICs that have multiple outputs, provide additional benefits if they offer multiphase functionality.

A multiphase converter consists of paralleled power trains which drive a common load. The switching signals for each of the power trains are out of phase with each other. For example, one power train might be opening a switch while another is closing a switch. Each power train continues to operate on the same clock frequency.

Multiphase operation provides many circuit performance benefits. Because the current draw is spread out more evenly within the switching cycle, the output current and voltage ripple are reduced in proportion to the number of phases without paying the price – in terms of increased switching losses – of operating at a correspondingly higher frequency. The reduction in the maximum instantaneous input current draw results in less ripple noise injected back into the supply. The overall result is higher efficiency and a smaller bill of materials (BOM) compared to single phase operation at the same clock frequency. In addition, multiphase regulators can respond to output load changes faster so they provide better transient response.

Most of these benefits become more evident for circuits designed for high current output, for example above 10 amps. However, there are also benefits for lower current circuits such as requiring smaller input and output filter capacitors.

Step-Down (Buck) Multiphase Switching Regulators (Internal Switch)
Step-Down (Buck) Multiphase Switching Controllers (External Switch)
Step-Up (Boost) Multiphase Switching Regulators (Internal Switch)