Energy monitor IC watches rails to 100V: 1% accurate, 12-bit resolution

September 25, 2014 // By Graham Prophet
LTC2946 is a high or low side charge, power and energy monitor for DC supply rails in the 0V to 100V range. An integrated ±0.4% accurate, 12-bit ADC and external precision time base (crystal or clock) enables measurement accuracy better than ±0.6% for current and charge, and ±1% for power and energy.

A ±5% accurate internal time base substitutes in the absence of an external one. All digital readings, including minima and maxima of voltage, current and power, are stored in registers accessible by an I²C/SMBus interface. An alert output signals when measurements exceed configurable warning thresholds, relieving the host of polling for data. The LTC2946 provides access to all the necessary parameters to accurately assess and manage board level energy consumption. Its wide operating range makes it suitable for monitoring board energy consumption in blade servers, telecom, solar and industrial equipment, and advanced mezzanine cards (AMC).

The LTC2946 can be powered from 2.7V to 5V directly, from 4V to 100V through an internal linear regulator, or beyond 100V through an internal shunt regulator. Two of the three general purpose input/output (GPIO) pins are configurable as an accumulator enable and alert output. The internal ADC operates in either a continuous scan mode or a snapshot mode. In shutdown mode, the device current consumption drops from 900 µA to 15 µA.

The LTC2946 is available in two options: the LTC2946 I²C interface has separate SDA input and output pins for standard or opto-isolated I²C, whereas the LTC2946-1 has an inverted SDA output for inverting opto-isolator configurations. Specified over the commercial, industrial, automotive and military temperature ranges, the LTC2946 comes in 16-pin MSOP and 4 x 3 mm DFN packages from $3.95 (1000).

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