MAXREFDES1049: Low EMI, 5V/3.5A, Synchronous Buck DC-DC Converter Using the MAX17504
|Input Type||VIN (MIN)
The MAXREFDES1049 is a DC-DC buck power supply that delivers up to 3.5A at 5V from a 7.5V to 60V supply voltage. It is designed for equipment that needs to pass the electromagnetic interference (EMI) compliance testing.
The MAXREFDES1049 employs techniques that use the buck regulators to generate voltage lower than the input voltage. This document explains how the MAX17504 peakcurrent- mode PWM converter can be used to generate 5V from an input voltage of 7.5V to 60V. This document also illustrates how to achieve high EMI performance using a proper filter with good PCB layout and shielding techniques. This reference design passed the conducted emission (CE) test of CISPR 22 class B.
The MAX17504 high-efficiency, high-voltage, synchronously rectified step-down converter with dual integrated MOSFETs operates over a 4.5V to 60V input. The converter can deliver up to 3.5A and generate output voltage from 0.9V to 90% VIN. Built-in compensation across the output voltage range eliminates the need for external components. The feedback (FB) regulation is accurate to within ±1.1% over -40°C to +125°C. The device is available in a compact (5mm x 5mm) TQFN lead (Pb)-free package with an exposed pad. Simulation models are available.
Designed, Built, Tested
This reference design describes the hardware shown above. It provides a detailed systematic technical guide to design a buck converter using the MAX17504 step-down controller. The EMI line filter selection and PCB layout are also introduced in this document. The power supply has been built and tested, details of which follow later in this document.