AD7280:  Lithium Ion Battery Monitoring System

The AD7280¹ contains all the functions required for general purpose monitoring of stacked Lithium Ion batteries as used in Hybrid Electric Vehicles. The part has multiplexed analog input and temperature measurement channels for up to six cells of battery management. An internal 3-ppm reference is provided to drive the ADC. The ADC resolution is 12 bits with a 1 Msps throughput rate offering a 1μs conversion time.

The AD7280 operates from just one VDD supply which has a range of 7.5V to 30V (with an absolute max rating of 33V). The part provides 6 pseudo differential analog input channels to accommodate large common mode signals across the full V_DD range. Each channel allows an input signal range, Vin(+) -- Vin(-), of 0V to 5V. The input pins assume a series stack of 6 cells. In addition the part can accommodate 6 external sensors for temperature measurement.

The AD7280 includes on chip registers which allow a sequence of channel measurements to be programmed to suit the applications requirements.

The AD7280 also includes an Alert function which generates an interrupt output signal if the cell voltages exceed an upper or lower limit defined by the user. The AD7280 has balancing interface outputs designed to control external FET transistors to allow discharging of individual cells. The AD7280 includes a Built In Self Test feature which internally applies a known voltage to the ADC inputs. There is a daisy chain interface which allows up to 50 parts to be stacked without the need for individual device isolation. The AD7280 requires only one supply pin which takes 7mA under normal operation, while converting at 1 Msps. All this functionality is provided in a 48 pin LQFP or 48 pin LFCSP package operating over a temperature range of −40°C to +105°C.

¹ Patents Pending

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