Abstract: When a push-button is used to manually reset a microprocessor (µP), ringing from the switch may cause a false reset output signal when the switch is press and de-pressed. Maxim's microprocessor supervisors have a debounced manual reset input to help ignore this ringing. Though they're not complicated, schemes for debouncing a pushbutton switch usually entail using several logic gates. It's easy to include such circuits in an ASIC. Adding a debouncer as a last-minute design change, however, can be inconvenient. In such cases, the circuit in the figure below can come in handy. The circuit, using only a 4-pin SO-package IC, squares up and debounces a pushbutton signal. IC1 is a reset chip with a reset output that goes high when its supply voltage drops below 2.65V or when its manual-reset input (MR-bar) goes low. MR-bar usually connects to a system-reset input, and reset connects to a µC, but the connections shown enable the device to debounce any signal. The internal one-shot provides an instant response to the first falling edge on the input and then delays any further response until 140msec after the last rising edge. The MAX812 shown inverts the pushbutton input; a similar device (MAX811) is noninverting. The ICs also incorporate a power-on reset function that asserts the reset output when VCC falls below a preset threshold and also asserts the output for 140msec after each application of power. Selecting an R-suffix part sets this threshold at its lowest value (2.63V), preventing false outputs in the debouncer except when the supply voltage fails. Using almost no real estate, this circuit squares up and debounces a pushbutton signal and extends it to at least 140msec. A similar version of this article appeared in the April 1, 2001 issue of EDN. 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 1858: Jun 01, 2001 MAX6384 SC70/µDFN 패키지로 제공되는 단일/듀얼 저전압, 저전력 µP 리셋 회로 전체 데이터 시트 (PDF, 232kB) 무료 샘플 MAX6385 SC70/µDFN 패키지로 제공되는 단일/듀얼 저전압, 저전력 µP 리셋 회로 전체 데이터 시트 (PDF, 232kB) 무료 샘플 MAX6386 SC70/µDFN 패키지로 제공되는 단일/듀얼 저전압, 저전력 µP 리셋 회로 전체 데이터 시트 (PDF, 232kB) 무료 샘플 MAX812 수동 리셋 입력 기능이 있는 4핀 µP 전압 모니터 전체 데이터 시트 (PDF, 192kB) 무료 샘플   다운로드, PDF 형식 (28kB)  AN1858, AN 1858, APP1858, Appnote1858, Appnote 1858