Battery capacity monitor operates up to 20V, reports via I²C

November 04, 2013 // By Graham Prophet
Linear Technology's LTC2943 is a multicell battery 'gas gauge' which makes direct measurements of 3.6V to 20V battery stacks. No level shifting circuitry on the supply and measurement pins is required to interface with multicell voltages, so total current consumption is minimised and measurement accuracy is preserved.

The LTC2943 is a true high voltage gas gauge that measures charge, voltage, current and temperature to within 1% accuracy — all of the essential parameters required to accurately assess battery state of charge (SoC).

The LTC2943 is best suited for multicell applications, including professional power tools and portable medical equipment. Battery current is measured by monitoring the voltage across an external, high side sense resistor and integrating this information to infer charge. A bidirectional analogue integrator accommodates either current polarity (battery charge or discharge), and a programmable prescaler allows for a wide range of battery capacities. Charge, voltage, current and temperature information are communicated to the host system over an I²C/SMBus-compatible 2-wire interface that is also used to configure the gas gauge. The host can program high and low thresholds for all measured parameters, which if tripped, signal an alert using either the SMBus alert protocol or by setting a register flag.

The LTC2943 comes in commercial and industrial versions, for 0°C to 70°C and -40°C to 85°C, respectively. In an 8-pin 3 x 3mm DFN package, pricing starts at $2.35 (1,000).

Linear Technology;