Abstract: This application note presents a single-pushbutton power-control circuit. The design consists of an ON/OFF control circuit comprised of a pushbutton, debouncer, and flip-flop. This circuit toggles the power output voltage by controlling an LDO. The design features the MAX6816 debouncer and MAX6484 LDO. This design idea appeared in the October 30, 2006 issue of Portable Design magazine. The design of a handheld device today requires that you simplify and reduce the controls to a minimum. A circuit that enables a single pushbutton to turn power on and off can be very useful. Figure 1 shows a single-pushbutton power-control circuit that consists of only a few small components, and consumes little power. The normally open (NO) single-contact pushbutton connects to a debouncer (the MAX6816, IC1) that guarantees a single-output edge (rise or fall) each time the button is pushed or released. The MAX6816's output drives the clock input of a flip-flop (IC2) wired as a T-type (toggle) flip-flop. The flip-flop output, in turn, controls a low-dropout (LDO) linear regulator (the MAX6484, IC3). The MAX6484 powers a handheld gadget, which turns on or off each time that the pushbutton is operated. The same circuit can also drive other types of power regulator, if the regulator features a logic-level power-management input. Figure 1. This normally open pushbutton connects to a debouncer, the MAX6816 (IC1) and IC2. This single-pushbutton ON/OFF control circuit lets you toggle the PWR OUT voltage by controlling the MAX6484 LDO (IC3). The 1MΩ resistor and 100nF capacitor connected to the flip-flop's CLR input ensure that the circuit always powers up in the same state (OFF) when PWR_IN is connected first. The ON/OFF control circuit (pushbutton, debouncer, and flip-flop) operates between 2V and 5.5V; it draws about 3.5µA when the supply voltage is 3.5V. The MAX6816 is available in a 4-pin SOT143 package, IC2 in an MO-187 package, and the MAX6484 in a 6-ball UCSP™ package. UCSP is a trademark of Maxim Integrated Products, Inc. 관련 부품   APP 4444: Sep 11, 2009 MAX6484 마이크로프로세서 리셋 회로가 내장된 300mA LDO 선형 레귤레이터 전체 데이터 시트 (PDF, 496kB) MAX6816 ±15kV ESD 보호, 단일/듀얼/옥탈, CMOS 스위치 디바운서 전체 데이터 시트 (PDF, 712kB) 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 (30kB)  AN4444, AN 4444, APP4444, Appnote4444, Appnote 4444