Atmel Announces Airbag System Power Supply IC
Atmel® Corp. announced the availability of its new monolithically-integrated ATA6264 airbag system power supply IC especially suited for high-end automotive airbag applications. The new device, manufactured in high-voltage 0.8-um BCD technology, provides a rich set of features, including measures against undervoltage conditions and battery cable loss, intelligent power sequencing, integrated watchdog and other diagnostic/monitoring functions.
The ATA6264 handles the voltage supply for complete airbag systems (which includes the sensors, microcontrollers, and firing devices) with programmable voltage levels. Communication with the microcontroller is carried out via a 16-bit SPI, while two ISO9141 interfaces enable the communication with diagnostic testers (one of these interfaces can be customer-programmed as a LIN interface).
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 ATA6264 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 15 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 (OTP), which is used to program the ISO interface, allows the user to program the output voltages of the buck converters (7.8 to 10.4V, 1.88 to 5.0V) and the highly-accurate linear regulator (3.3 and 5.0V) during the production process (end-of-line programming by an in-circuit tester). If the linear regulator's 100-mA current capability is not sufficient, the user can extend it using an external bypass transistor. The ATA6264 supports dual microcontroller systems with intelligent power sequencing, preventing the buck converters' output voltages from exceeding a predefined limit and reliably defining which one of the microcontrollers 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. 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 measurements – especially suited for monitoring the buckle switches of an airbag system – are 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 microcontroller can react. The safety philosophy is further expanded by an integrated watchdog timer and reset circuitry. In the event of a microcontroller failure or improper voltages, the ATA6264 sends a reset command. The device meets strict automotive qualification demands (it is protected against conducted interferences according to ISO/TR7637/1 EMC and ESD protection).
Samples are available now in RoHS-compatible QFP44 packages with pricing starting at US $3.30 for 10k-piece quantities.
