Reference Design for a High-Current Power Supply with Lossless Current Sensing Using the MAX5060

Introduction

Today's data processing elements demand higher currents from power supplies to achieve higher speed. Lossless current sensing and ground bouncing are key challenges for accurate control of output voltage and current in these applications.

The MAX5060 PWM buck power-supply controller uses an average-current-mode control technique to track the load current, and it employs differential sensing to accurately control the output voltage. In this reference design, the series resistance (DCR) of the inductor is used for current sensing to avoid power loss in the current-sense resistor.

This design shows a solution for implementing a high-current (30A) power supply with high system efficiency and good load regulation. The complete schematic, bill of materials (BOM), efficiency measurements, and test results are included below.

Specifications and Design Setup

This reference design achieves the following specifications.

• Input voltage: 12V ±10%
• Output voltage: 1.5V
• Output current: 30A
• Output ripple: ±15mV
• Input ripple: ±250mV
• Efficiency: > 88% with half of full load (15A)
• Switching frequency: 275kHz
• Footprint size: 5cm × 3.3cm
• The schematic for this reference design is shown in Figure 1, and the BOM is given in Table 1. In this design, the MAX5060 is used in a buck configuration.