Intelligent Automotive Battery Sensor

Shunt Resistors and Evaluation Electronics Offer Two Key Components

- Andreas Heder

Driver assistance systems require a control unit to switch on vital assistance or to ensure availability. Vishay's intelligent battery shunt resistor and Infineon's automotive PSoC 4 HVPA monitor residual energy and distribute loads appropriately to enhance reiliability and availability.

Battery monitoring plays an essential role in ensuring a reliable power supply for high-availability control units in automotive driver assistance systems, as does sensor technology. The combination of the two components is critical in designing an intelligent battery sensor.

Parameters such as battery current and voltage are measured to monitor the battery in the vehicle. The electronics use these parameters to calculate the residual energy stored in the battery, among other variables. Based on this, a control unit can decide which loads may be switched on or must be switched off to ensure that vital assistance functions remain available.

To measure the current, an important component in any battery sensor is the sensing element, such as shunt resistors, which are the focus of this article.

The advantage of shunt resistors is that they provide a simple linear relationship between the measurand and the output signal. According to Ohm's law, the voltage drop across the shunt is proportional to its constant resistance and the current flowing through it. This makes shunts suitable for DC and AC currents as well as for both current directions. The sensitivity to interference with respect to temperature is known from the data sheet and can be calculated if the actual temperature value is known.