Power and current monitor enables board optimisation

The LT2940 has been designed to provide the necessary circuits to measure, monitor and control power in situations where both the current and voltage may vary due to supply voltage uncertainty, component parametric changes, transient conditions or time varying signals. Unlike traditional power monitors that rely on data converters and multiplying registers to calculate power, the LT2940 uses a true four quadrant analogue multiplier which Linear says results in 5% power measurement accuracy and 3% current measurement accuracy. The LT2940 is suitable for use in line cards and servers, power sense circuit breakers, power control loops and a wide variety of metering applications. The LT2940 measures a high side current and differential voltage, and calculates the instantaneous power at a bandwidth exceeding 500kHz. Bidirectional high side currents and bipolar voltage differences are handled by a four quadrant multiplier and push-pull output stage, which allow the device to indicate forward and reverse power flow. After current and voltage measurements are taken, current and power levels can be scaled, filtered and monitored separately via their respective proportional to current and proportional to power current outputs. Meanwhile, an integrated comparator with complementary open collector outputs can be used to create PWM control loops, or provide simple logic of, for example, an over-power pin, an LED indicator alarm, a mosfet load cutoff switch, an external fan, or a binary counter for metering applications. The LT2940 is offered in commercial and industrial versions, supporting operating temperature ranges from 0 to 70^ºC and -40 to 85^ºC, respectively.