Freescale Announces Intelligent Sensor for Automotive Battery Monitoring

Battery voltage, current, and temperature using automotive-certified sensors
Providing excellent cost-effective solutions for precise monitoring

March 8, 2011, Seoul — Freescale Semiconductor ( www.freescale.co.kr, Korea Representative: Yeonho Hwang) announced the MM912J637 Intelligent Battery Sensor (IBS), which accurately measures the voltage, current, and temperature of lead-acid batteries and calculates battery status even under strict automotive electronic component conditions. With the recent launch of hybrid vehicles, the increase in overall electronic components within vehicles, and the introduction of start-stop systems, the ability to accurately measure these battery parameters is becoming increasingly important.

The MM912J637 IBS enables precise measurement of key battery parameters in automotive and industrial applications, providing designers with a robust and cost-effective solution. This device integrates a 16-bit S12 microcontroller and SMARTMOS analog control integrated circuits into a single package solution to deliver low power suitable for vehicles. The MM912J637 IBS fully meets AEC-Q100 automotive compliance for operation over a temperature range of -40°C to +125°C and is available in a small 7x7mm QFN package.

The increasing use of electricity in vehicles today means placing a load on the battery. Vehicle failures caused by the electrical system can be easily traced to the lead-acid battery and, generally, prevented by checking the battery's precise condition. The battery must be able to supply sufficient energy to operate the engine and serve as a passive power source to support new hybrid vehicle features, such as start-stop and intelligent alternator control. Furthermore, the power consumption of the IBS must be as low as possible for energy efficiency.

"With the increase in electric components in hybrid and electric vehicles and the emergence of start-stop systems, it is crucial to always accurately monitor the vehicle's battery, especially in demanding vehicle conditions," said Gavin Woods, Vice President and General Manager of Freescale's Analog, Mixed-Signal, and Power business unit. Freescale ensures precise monitoring of critical battery parameters and is providing the industry's first cost-effective solution that fully meets automotive certification requirements. These battery parameters can be shared with other vehicle systems and the driver, allowing the driver to know the battery status and feel reassured.

Freescale's fully integrated battery monitoring device communicates using the Local Interconnect Network (LIN). It features a 2-channel, 16-bit analog-to-digital converter (ADC) for the simultaneous measurement of battery voltage and current, and an independent 16-bit ADC for temperature measurement. The IBS provides high-resolution, accurate monitoring even under worst-case conditions, enabling appropriate prediction of battery quality, charge, and functional status. Automotive-certified in-vehicle LIN networks communicate these parameters on a regular or on-demand basis.

The MM912J637 supports precise current measurement via an external shunt resistor at the negative electrode of the battery and precise battery voltage measurement via a series resistor at the positive electrode. An integrated temperature sensor combined with a battery mount precisely measures the battery temperature.

MM912J637 IBS Characteristics:
• Battery voltage measurement
o Dedicated 16-bit secondary ΣΔ ADC, full measurement range 3.5–28V, 5–18V range