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. 相关型号   APP 4444: Sep 11, 2009 MAX6484 300mA LDO线性稳压器，内置微处理器复位电路 完整的数据资料 (PDF, 496kB) MAX6816 ±15kV ESD保护、单/双/八通道、CMOS开关去抖器 完整的数据资料 (PDF, 712kB) 免费样品 自动更新 需要自动接收最新发布的应用笔记吗？请订阅EE-Mail™ (English only)。 我们期待您的反馈！ 喜欢？不喜欢？有待改善？或为我们提供建议？请与我们联系 — 我们将根据您的意见或建议改善我们的工作。 网页评价或提供建议   下载，PDF格式 (30kB)  AN4444, AN 4444, APP4444, Appnote4444, Appnote 4444