Susie Maestre

user Electronics Engineer

city Innovuze Solutions Inc.

  • 30A Power/Energy Monitor with Integrated Sense Resistor

  • Created: Nov 10, 2016

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In industries or in any electronic systems, it is necessary to properly monitor power and energy consumption. This is to ensure that the system is working within safety measures. Since the demands and rates of power are increasing, energy monitor equipment is highly needed, which aims to reduce cost by adequate power saving and fault detection. Also, energy and power monitoring equipment is useful in reducing risk in manufacturing industries.

This reference design features LTC2947, a high precision power and energy meter with an internal 30A sense resistor. This design is an easy solution to digitally monitor the parameters needed to accurately manage system power and energy consumption. Parameters such as current, voltage, power, charge and energy data are accessible via a simple I2C/SPI interface. The operating voltage ranges from 4.5V to 15V for AVCC/ DVCC and 1.8V to 5V for OVDD. The LTC2947 utilizes three delta-sigma (ΔΣ) ADCs to simultaneously measure current and voltage, and calculate power for true power readings. An integrated temperature-compensated sense resistor maximizes measurement accuracy over temperature and simplifies space-constrained designs. At high current levels, power dissipation typically mandates the use of a low value sense resistor, which also reduces input voltage signal. As a result, current measurement accuracy becomes susceptible to thermoelectric voltages and board layout. The LTC2947’s integrated temperature-compensated 300µΩ sense resistor is insensitive to such disturbances and provides low power dissipation and high accuracy across the entire operating range, producing a ±30A monitoring solution that is superior to external sense resistor solutions. The LTC2947 keeps track of the minimum and maximum measured values for each of the measured quantities. Thresholds can be set for each parameter, and the LTC2947 will set the corresponding bit in the Alert register and optionally alert the host by pulling low on the ALERT pin when a threshold is exceeded.

This design is ideal for cost-effective power and energy monitoring in industries. This is also a convenient tool to monitor both power and energy in servers, telecom infrastructure, industrial, electric vehicles, and photovoltaics.