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Case Study 19 Solution for Safe Gas Metering Applications Natural gas is one of the most widely-used fossil fuels in the world, and as a result gas meters have become ubiquitous in residential, commercial, and industrial settings to measure gas consumption. The integrated circuits used in today's gas meters are supplied by batteries, and to keep gas suppliers' cost down they are expected to last for many years without maintenance. Thus, low power consumption is a key consideration for manufacturers in gas meter design. In addition, modern gas meters must be equipped with automatic shut-off valves to interrupt the gas supply during events such as earthquakes, to reduce the risk of re and explosion resulting from gas leaks. These valves are motorized and run off the same battery supply as the meter's other circuitry, so engineers face the added challenge of integrating a motor driving circuit that has minimal impact on the meter's overall battery life. STMicroelectronics' STSPIN250 low voltage brushed direct current (DC) motor driver answers this challenge convincingly with a device specically designed for battery-powered scenarios. With very low operating voltage and standby consumption of less than 80nA, it can also be forced into a zero-consumption state for even greater power saving. Thus the STSPIN250 can drive the valve motor reliably and with negligible impact on battery duration, rendering it uniquely suited for use in automatic gas shut-off valve designs. By Enrico Poli, STMicroelectronics mouser.com/stmicroelectronics-stspin-drivers/ STSPIN820 Smooth & silent stepper motor driver World's smallest, 256 steps capable, and 45V rated motor driver • Extreme position accuracy and motion smoothness: with up to 1/256 microsteps per full step • Integration of the PWM control and the power stage made by 500m R DS(ON) MOSFETs guarantees one of the best performance-cost trade-offs • Compact 4 x 4mm QFN makes it the smallest integrated microstepping driver with these ratings

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