1 Introduction

Every buck regulator will have a specified maximum output current rating capability that the device can handle before an over-current condition is triggered. In this over-current condition the device will shut-down, stop switching, and check if the fault is removed before switching is resumed. Normally if a design calls for a higher output current requirement above the device’s maximum rated output current limit, a new device must be selected. However this would require a new schematic and PCB layout design if the device is not pin-to-pin compatible with the original layout.

With a simple external differential op-amp circuit two single-output buck regulators can be configured in a two-phase design to allow twice the load current capability of a single buck regulator. This provides customers the following benefits:

1. Tying two regulator outputs together to share current allows the spread of power loss between two regulators leading to lower tempt rise and overall thermally robust design. This removes the potential need for designing with an external heatsink which increases system design complexity, size, and overall cost.
2. Implementing 180 degrees phase shift circuit provides the following benefits:
   1. Each path will have less switching losses. Doing this creates a design that leads to better EMI and thermal performance.
   2. Phase shift circuits provide input and output ripple current cancellation. For more details refer to Section 8.1.2 from the LM5119-Q1 data sheet.
3. Easier to design than a dual phase controller since power MOSFETS are already integrated into the regulator/converter.