Abstract: The following application note demonstrates a simple circuit using a charge pump and a microprocessor supervisor to disconnect a low voltage supply from a load. The circuit uses a P-channel MOSFET to disconnect the load from a 1.5V supply. Power supplies often include a circuit that disconnects the load when the supply voltage drops too low (when a battery is nearly discharged, for example). A p-channel MOSFET connected between supply and load is the typical approach. However, a 1.5V single-cell battery or other low-voltage supply is not sufficient to fully turn on the MOSFET. For such low-voltage systems, consider the circuit of Figure 1. Figure 1. This low-voltage circuit disconnects the load when the supply voltage drops below a predetermined threshold (1.3V in this case). A small inverting charge pump (IC1) generates a negative voltage approximately equal to the input supply (VCC). That voltage connects to the ground terminal of a microprocessor supervisor (IC2), which monitors the voltage difference between its own VCC and GND pins. As long as this difference is greater than the supervisor's internal trip-voltage threshold, the RESET output voltage is driven to the charge-pump output (approximately -2VCC), which provides a gate-source voltage adequate to keep the MOSFET on. When the monitored voltage drops below the threshold of the supervisor, its RESET output goes up to VCC and turns the MOSFET off. The supervisor shown has a threshold of 2.6V. Because the voltage it detects is twice the supply voltage, this circuit disconnects the load when the supply voltage drops below 1.3V, making it suitable for use with a typical 1.5V battery. Other internal threshold voltages are available. We Want Your Feedback! 의견을 보내주세요! 위 내용이 도움이 되셨나요? 여러분의 의견을 기다립니다 — Maxim은 보내주신 정정이나 제안사항을 반영하고 있습니다. 이 페이지를 평가하고 의견을 보내주십시오. 자동 업데이트 관심있는 분야의 애플리케이션 노트가 나올 때 자동으로 업데이트 받고 싶으세요? 그렇다면 EE-Mail™을 신청하십시오. 추가 정보   APP 2237: Sep 22, 2003 MAX1697 셧다운 기능이 있는 60mA, SOT23 반전형 차지 펌프 전체 데이터 시트 (PDF, 528kB) 무료 샘플 MAX6327 3핀, 초저전력 SC70/SOT µP 리셋 회로 전체 데이터 시트 (PDF, 160kB) 무료 샘플   다운로드, PDF 형식 (19kB)  AN2237, AN 2237, APP2237, Appnote2237, Appnote 2237