Voltage vs. Current Mode Control Curent Sharing in a PolyPhase DC/DC Converter - LTC3731, LTC3853, LTC3850

Current sharing performance is critical for PolyPhase DC/DC converter to balance the thermal stress and properly size the power components. The PolyPhase converter can be controlled by either voltage or current mode control scheme. With voltage mode control, the active current sharing is achieved with a complicated external current sharing loop, which is usually slower than the inner voltage feedback loop. With current mode control, such as implemented in the LTC3731 or LTC3850, the current sharing can be implemented very easily with its fast current loop. As a result, though both voltage and current mode control can provide good steady-state (DC) current sharing among channels, the current mode control provides significantly superior current sharing performance and reliability during transients.