Switch Your Switch

　　Switch Your Switch

　　技术的进步使得磁性传感器比以往任何时候都更小、更低功率和更敏感。由于这些进步，磁阻（MR）传感器，它总是提供显着的好处霍尔效应和里德交换机，应着眼于设计新的系统时，需要一个位置开关。

　　MR传感器是固态开关，没有机械部件来操作开关。他们是全极性的性质，将动时是南北极的磁铁的磁场在感应范围。MR设备的感应方向是在IC的平行平面，它不同于霍尔传感器，它感应垂直于IC的磁场（图1）。该开关关闭时，磁场被删除从传感器。此外，MR传感器比霍尔效应更敏感的磁场，并可以提供更多的灵活性，并要求在应用中使用的成本较低的磁铁。

　　Figure 1： A Hall sensor responds to magnetic fields placed perpendicular to its body while an MR device responds to magnetic fields applied in a direction parallel to the sensor.

　　Advances in circuit design now allow for magnetic sensors to utilize much lower power than ever before. Most magnetic sensor manufacturers offer sensors that only use microamp supply current to power the sensor. As this technology continues to develop， more design engineers are turning to low-power sensors to replace mechanical switches in battery-powered applications.

　　Honeywell recently introduced their new Magnetoresistive Sensor ICs， Nanopower Series that includes two sensors， SM351LT and SM353LT， which draw only 360 nA and 310 nA， respectively， at 1.8 VDC. These sensors are housed in a tiny SOT-23 package （Figure 2）， have an operating temperature of -40˚C to 85˚C， and are a great switch for most battery-powered applications.