Data terminal equipment (DTE), such as wireless LAN and wireless local loop, may require data and power on the same cable. A high voltage power source of 24V is required to reduce the voltage drop in the cable. Isolation is provided by the 12V power-supply. For a system with one or two ports, a custom-designed DC-DC converter is more suitable than power modules, or "bricks", since bricks tend to be bulkier and are more expensive. They are more suitable for systems that support more ports, where the power demand is higher. The MAX668 is an excellent choice for the design of a DC-DC step-up converter. The MAX668, a current-mode controller, operates in the PWM mode at medium and heavy loads, providing high-efficiency and low-noise. With power levels greater than 20W, efficiencies of more than 90% are achievable. Figure 1. The circuit of Figure 2 has a 24V output and can deliver current up to 3 amperes, enough to power a system with two ports. A switching frequency of 500kHz was chosen as a compromise between switching loss and the size of inductor L1. Increasing the value of gate resistance R7 will reduce EMI noise, but increase switching loss. A value of 4.7Ω was chosen as a compromise. At an input voltage of 12V, a full load of 3 amperes and an output of 24V, the conversion efficiency was 93%. Figure 2. 관련 부품   APP 910: Dec 27, 2001 MAX668 1.8V ~ 28V 입력, µMAX 패키지로 제공되는 PWM 스텝 업 컨트롤러 전체 데이터 시트 (PDF, 304kB) 무료 샘플 자동 업데이트 관심 분야의 애플리케이션 노트가 나올 때 자동으로 업데이트를 원하십니까? 그렇다면 EE-Mail™을 신청하십시오. We Want Your Feedback! 의견을 보내주세요! 위 내용이 도움이 되셨나요? 여러분의 의견을 기다립니다 — Maxim은 보내주신 정정이나 제안사항을 반영하고 있습니다. 이 페이지를 평가하고 의견을 보내주십시오.   다운로드, PDF 형식 (35kB)  AN910, AN 910, APP910, Appnote910, Appnote 910