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Power supply IC targets high-end car airbag apps

Posted: 20 Oct 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Atmel? ATA6264? airbags? power supply? BCD?

Atmel's ATA6264 power supply IC for car airbags

Atmel Corp. has announced the availability of an airbag system power supply IC particularly suited for high-end automotive airbag applications. The monolithic ATA6264, manufactured in high-voltage 0.8?m BCD technology, offers a set of features not available from any other competitive device, said Atmel. These features include measures against undervoltage conditions and battery cable loss, intelligent power sequencing, integrated watchdog and other diagnostic/monitoring functions. In addition, the new device promises the highest accuracy as well as unrivalled flexibility due to its programmability.

ATA6264 handles the voltage supply for complete airbag systems (which includes the sensors, MCUs and firing devices) with programmable voltage levels. Communication with the MCU is carried out via a 16bit SPI, while two ISO9141 interfaces enable the communication with diagnostic testers, one of these interfaces can be customer-programmed as a LIN interface.

Flexibility
The voltage supply section of the ATA6264 consists of a boost converter with adjustable voltage, two buck converters and a linear regulator that can be customer-programmed. This flexibility allows the user to adapt the device to the needs of different system requirements and thus simplifies stocking issues. The output voltage of the boost converter is defined by an SPI command and an external voltage divider, and can be adjusted from 15V to 40V. The high supply voltage charges the capacitors to feed the system in the event of an undervoltage condition, such as a disconnected battery.

An integrated one-time-programmable memory, which is used to program the ISO interface, allows the user to program the output voltages of the buck converters (7.8-10.4V, 1.88-5V) and the linear regulator (3.3V and 5V) during the production process (end-of-line programming by an in-circuit tester). If the linear regulator's 100mA current capability is not sufficient, the user can extend it using an external bypass transistor. The new device supports dual MCU systems with intelligent power sequencing, preventing the buck converters' output voltages from exceeding a predefined limit and reliably defining which MCU is activated first.

As a unique feature, if the airbag power supply IC detects an undervoltage condition and the loss of the supply voltage (for example, a battery cable disconnect during a crash), then it automatically draws its energy from a back-up capacitor connected to the boost converter.

Safety
The diagnosis and monitoring section of the ATA6264 adds safety to the system and helps minimize the number of system components. Five integrated voltage sources for resistor measurementsespecially suited for monitoring the buckle switches of an airbag systemare available.

Temperature diodes embedded in both buck converters and the linear regulator measure the chip temperature. In the case of an access temperature condition, a status bit is set and the MCU can react.

The safety philosophy is further expanded by an integrated watchdog timer and reset circuitry. In the event of MCU failure or improper voltages, the device sends a reset command. It meets automotive qualification demands and has EMC and ESD protection.

Samples are available today in RoHS-compatible QFP44 packages with pricing starting at $3.30 for 10,000-piece quantities.




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