Microelectromechanical system (MEMS) devices often require high DC-bias voltages (40V to 100V) at low current (< 1mA), but the available supply voltage may be < 12V. A DC-DC converter that combines inductive and capacitive step-up circuitry (Figure 1) achieves the high voltage without need for a costly transformer. Figure 1. A high-voltage DC-DC converter (U1) converts a typical 5V input to 36V, and a 2-stage charge pump boosts that voltage to more than 100V. U1 is a step-up DC-DC converter capable of output voltages to +36V, and a 2-stage charge-pump converter (D2-D5 and C1-C4) nearly triples the U1 output. The R1/R2 divider provides feedback for regulating the circuit's output voltage. Use these equations to calculate the resistor values: For lower output voltages (< 70V), remove D4, D5, C3, and C4 to produce a single-stage charge pump. Similarly, you can add another stage to produce voltages higher than 100V. An optional post filter (R3 and C5) reduces the output ripple to < 10mVP-P. Figure 2 illustrates the variation of output voltage with output current. Figure 2. The output voltage in Figure 1 is well regulated for load currents up to 0.7mA. A similar version of this article appeared in the August 18, 2002 issue of EET magazine. 관련 부품   APP 1751: Sep 27, 2002 MAX5025 500kHz, 36V 출력, SOT23, PWM 스텝 업 DC-DC 컨버터 전체 데이터 시트 (PDF, 264kB) 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 (37kB)  AN1751, AN 1751, APP1751, Appnote1751, Appnote 1751