MAXREFDES1017: Optional single-output SEPIC converter

The MAX16990 is a high-performance, current-mode PWM controller with 4µA (typ) shutdown current for wide input voltage range boost/SEPIC converters. The 4.5V to 36V input operating voltage range makes this device ideal in automotive applications such as for front-end “pre -boost” or “SEPIC” power supplies and for the first boost stage in high power LED lighting applications. An internal low-dropout regulator (PVL regulator) with a 5V output voltage enables the MAX16990 to operate directly from an automotive battery input. The input operating range can be extended to as low as 2.5V when the converter output is applied to the SUP input. The MAX16990 operates in different frequency ranges. It can be synchronized to an external master clock using the FSET/SYNC input. In addition, the MAX16990 has a factory-programmable spread-spectrum option. It is available in compact 12-pin TQFN and 10-pin µMAX^® packages.

Key Features

• Minimized Radio Interference with 2.5MHz Switching Frequency Above the AM Radio Band
• Space-Efficient Solution Design with Minimized External Components
  • 100kHz to 1MHz Switching-Frequency Range
  • 12-Pin TQFN (3mm x 3mm) and 10-Pin µMAX Packages
• Spread Spectrum Simplifies EMI Management Design
• Flexibility with Available Configurations for Boost, SEPIC, and Multiphase Applications
  • Adjustable Slope Compensation
  • Current-Mode Control
  • Internal Soft-Start (9ms)
• Protection Features Support Robust Automotive Applications
  • Operating Voltage Range Down to 4.5V (2.5V or Lower in Bootstrapped Mode), Immune to Load-Dump Transient Voltages Up to 42V
  • PGOOD Output and Hiccup Mode for Enhanced System Protection
  • Overtemperature Shutdown
  • -40°C to +125°C Operation

This board is not available for purchase.

A single-output SEPIC converter using the MAX16990 is demonstrated for a 18V to 32V input voltage range application. The output is selectable to be equal to either +24V or +5V using configurable jumpers present on the PCB. The power supply delivers up to 0.9A max load current.

Designed, Built, Tested

This document describes the hardware show in Figure 1. It provides a detailed systematic technical guide to designing a SEPIC converter using Maxim’s MAX16990 current mode controller. The power supply uses uncoupled inductors and has been built and tested, details of which follow later in this document.

Design Resources