Auto Electronics

Atmel announces airbag power supply and high temperature driver ICs

Atmel Corporation has introduced four new semiconductor products for automotive applications. They are a monolithically integrated airbag system power supply IC for high-end automotive airbag applications and three new driver ICs based on high-voltage SMARTIS technology for AECQ100, Grade 0 high-temperature applications up to 150 °C.

The ATA6264 airbag chip, manufactured in high-voltage 0.8 µm BCD technology, includes protection against undervoltage conditions and battery cable loss and provides intelligent power sequencing, an integrated watchdog, and other diagnostic/monitoring functions. The chip handles the voltage supply for complete airbag systems, including sensors, microcontrollers and firing devices, with programmable voltage levels. Communication with the microcontroller is accomplished via a 16-bit SPI while two ISO9141 interfaces enable communication with diagnostic testers. One of the 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. The output voltage of the boost converter is defined by an SPI command and an external voltage divider, and can be adjusted from 15 V to 40 V. 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, used to program the ISO interface, allows the user to program the output voltages of the buck converters (7.8 V to 10.4 V, 1.88 V to 5.0 V) and the linear regulator (3.3 V and 5.0 V) during production. 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 which microcontroller is activated first.

If the airbag power supply IC detects an undervoltage condition and the loss of the supply voltage, it automatically draws its energy from a back-up capacitor connected to the boost converter. The diagnosis and monitoring section of the ATA6264 includes five integrated voltage sources for resistor measurements. Temperature diodes embedded in both buck converters and the linear regulator measure the chip temperature. In the event of a microcontroller failure or improper voltages, the ATA6264 sends a reset command. The device is protected against conducted interferences according to ISO/TR7637/1 EMC and ESD protection.

The driver ICs ATA6824, ATA6827 and ATA6832 are designed for use in hot environments. The SMARTIS technology on which they are based uses an Silicon-On-Insulator (SOI)) substrate that minimizes junction leakage and is said to provide superior latch-up immunity.

The ATA6827 is a fully-protected triple half-bridge driver with integrated power stages to control up to three different loads by a microcontroller. Each of the three high-side and three low-side drivers are capable of driving currents up to 1.0 A, and the chip supports the application of H-bridges to drive dc motors. Reverse, brake, and high impedance operation modes are controlled by the SPI interface.

The ATA6832 provides an additional PWM functionality with up to 25 kHz, enabling a dc motor control to be generated without any audible noise caused by the PWM signal. If higher output currents are required, the ATA6824 MOSFET driver IC includes, in addition to the H-bridge driver, a 5 V/3 V voltage regulator for microcontroller supply, a window watchdog and a serial interface. The ATA6824 includes motion control functionality on-chip so that only the direction command and the PWM signal for the speed information need to be provided by the microcontroller.

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