Abstract: This application note uses a high-side current-sense amplifier to monitor the current from a negative supply voltage. The circuit uses the IC's wide common-mode input range to amplify a small Vsense signal at the negative supply and level shift it up to a positive output voltage. All dedicated current-sense amplifiers are designed for high-side sensing on a positive supply, but you can adapt them to monitor a negative supply (Figure 1). The positive supply pin (V+) connects to the system's positive supply, and the ground pin (GND) connects to the negative supply (VEE). That arrangement monitors the negative supply while providing a positive output voltage for the external interface (typically an A/D converter). The RS+ pin of the current-sense amplifier (U1) connects to the load, and the RS- pin connects to the negative supply. Figure 1. Connecting this positive-supply-current monitor (U1) as shown lets it monitor a negative current while generating a positive output voltage for the ADC. U1's current-source output drives a current that is proportional to load current flowing to ground (not to the GND pin). Output resistor RO converts the current to a voltage, which is then digitized by an ADC (optional): The maximum output voltage is limited by saturation in the internal transistors (which occurs at approximately V+ -1.2V). Thus, V+ must exceed the full-scale output by at least 1.2V. If, for instance, the full-scale output is 1V, then V+ ≥ +2.2V. To meet the device's maximum and minimum operating voltages, 0 ≥ VEE ≥ -(32 - V+) and (V+ - VEE) ≥ +3V. Figure 2 shows the variation of current-measurement accuracy with load current. Figure 2. The Figure 1 current-sensing error varies with load current as shown. 相关型号   APP 2011: Jun 20, 2003 MAX4172 低成本、精密的、高边电流检测放大器 完整的数据资料 (PDF, 96kB) 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 (33kB)  AN2011, AN 2011, APP2011, Appnote2011, Appnote 2011