LM27403EVM-POL600: 1.8V @ 30A, 3 ~ 20V in

This user's guide offers perspective regarding point-of-load (POL) DC/DC regulation circuit design and implementation. Specifically, it describes a cost-effective solution to address the challenges a system designer can encounter when a high density and efficient POL regulator is required and PC board real estate is at a premium. Using the LM27403 voltage-mode PWM controller and a Power Block NexFET™ in an embedded module style solution, the LM27403EVM-POL600 synchronous buck regulator delivers an output current up to 30 A. High conversion efficiency is a key parameter in this design—translating into lower power loss, less package temperature rise for a given power throughput, and enabling a higher power density form factor. PCB source and gerber files, as well as component views and fabrication drawings, are available in PowerLab™ for this design.

The LM27403EVM-POL600 represents a standalone POL module with benchmark power density surface mounted on a host board as a mother-daughter configuration. The POL module itself is an independent sub-assembly that is ultra-compact, versatile, tailored to high-volume SMT manufacturing, and fully proven and tested before SMT placement on the host board.

In practice, a POL module such as this is typically parallel stacked onto the system motherboard wherein power and signal connections are realized using SMT connections. As such, the module can be flexibly deployed across multiple systems and applications, greatly easing the design burden of a system engineer. Alternatively, the design is realized as a voltage-regulator-down (VRD) implementation with the components placed directly on the motherboard.

High density and small footprint are the main design tenets, with efficiency as a key performance metric.
An output voltage with better than 1% setpoint accuracy is adjustable between 0.6 V and 5.5 V simply by changing a trim resistor. With an output current up to 30 A, the switching frequency is 600 kHz and synchronizable to a higher frequency if required. Nominal input voltage is 12 V but can vary from 3 V to 20 V with suitable adjustment of the programmable UVLO.

The LM27403EVM-POL600 is designed specifically to demonstrate the LM27403 PWM controller in a typical 12-V bus to low output voltage, low duty-cycle application.