Step-up dc-dc converters that operate from small input voltages often have correspondingly low maximum breakdown voltages of 5V to 6V, which limits the maximum output voltage available from such devices. Adding an autotransformer lets you double VOUT without exceeding the IC's breakdown voltage. A properly wound center-tapped inductor acts like a transformer with a 1:1 turns ratio. Combined with an IC that normally boosts single-cell inputs as high as 6V, it produces a regulated 9V output with no more than 4.5V across the IC (Figure 1). The circuit is suitable for use in smoke alarms and other battery-powered equipment. It delivers 30mA at 9V from a 1.1V input, and as much as 90mA at 9V from a 1.5V input. Figure 1. An autotransformer allows a low-voltage step-up converter to boost single-cell inputs as high as 10V. A similar circuit for 2-cell inputs(Figure 2) delivers 30mA at 9V from 1.6V, and 80mA at 9V from 3.6V. Figure 2. Similar to Figure 1, this circuit accepts 2-cell inputs and generates regulated outputs as high as 10V. 相关型号   APP 496: Jul 09, 1998 MAX857 3.3V/5V或可调输出、升压型DC-DC转换器 完整的数据资料 (PDF, 820kB) 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 (35kB)  AN496, AN 496, APP496, Appnote496, Appnote 496