Supply monitor simplifies board level energy measurements

Most power and energy monitoring ICs use an external sense resistor to measure current, however the LTC2947 power and energy monitor from Linear Technology integrates a 300µΩ temperature-compensated sense resistor to alleviate these concerns.

The 24mm2 device provides up to 1.2 per cent accurate energy readings at up to ±30A. When measuring a full-scale current of 30A, the voltage drop over the integrated sense resistor is approximately 9mV, causing power dissipation of approximately 0.25W or approximately 10mW when measuring a 6A rail. The low offset of 6mA or 1.8 microV offers high dynamic range, says the company.

Three integrated delta sigma ADCs and an internal or external precision time base (crystal or clock) enable accurate measurement of multiple parameters, including current, voltage, power, charge, energy, temperature and time. All digital readings, including minimum and maximum values, are stored in registers accessible by a selectable I2C or SPI interface. An alert signal notifies the host when measurements exceed configurable warning thresholds. The monitor provides access to parameters to accurately assess and manage board level energy consumption. Rail-to-rail operating range monitors current levels during short-circuit or blackout situations without additional circuitry.

It is specified over commercial and industrial temperature ranges, and is offered in a 32-lead 4.0 x 6.0mm QFN package.


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