The unique features of the DRV5000 family of Hall effect sensors, combined with the ultra-low power capabilities of the MSP430TM MCU, enable for the first time, smart physical presence-detection systems such as door or window security, and e-meters to remain directly powered from a single low cost CR2032 coin cell for over two decades of continuous operation.
Compared to an always-active sensor system, an intelligent Hall-effect sensor system can be designed with its current consumption reduced from what are typically milliamps to less than a microamp — a reduction of over 1000x. This is achieved by combining the fast start-up time and wide-range operating voltage of the DRV5000 Hall sensor with the ultra-low-power capabilities of the MSP430 MCU. Such a sensing system with extremely low power consumption enables physical presencedetection applications, such as door or window security systems, and e-meters to be directly powered from a single low-cost CR2032 coin cell for over two decades of continuous operation.
The techniques described in this paper that enable ultra-low power (ULP) sensing include:
- Operating the system in ultra-low power standby mode as the normal mode
- Duty-cycling the sensor
- Exercising power-aware firmware
The simplified example circuit in Figure 1 shows a very low-cost system that does not require any external calibration. The complete sub-microamp, intelligent Hall-sensing system detects the presence of a magnet and is powered directly from a CR2032 battery.