Automotive Made Easy with X-FAB

X-FAB is the only foundry offering automotive-qualified SoC technologies featuring the combination of sensors, signal conditioning, high-voltage non-volatile memories (NVM), analog and digital elements. NVM options include embedded Flash solutions for program and data storage as well as OTP options for trimming. In addition to the technical SoC solution, X-FAB provides full support to enable zero ppm strategies from design support through to mass production.


Automotive Solenoid Driver - Block Diagram


Automotive Solenoid Driver

Solenoids are electromechanical actuators. They can be part of relays or hydraulic valves. Due to the high inductivity of the coil the power driver stages have to not only switch the current in the on-state but also need to take care of the freewheeling currents or resulting voltages in the event of switching the solenoid off. Due to the high current consumption of the solenoid, it is switch in PWM (Pulse Width Modulation) mode. The microprocessor controls the PWM cycles. The low side driver (LS Control) switches to on during the active PWM cycle, whereas the high side driver (HS Control) controls the freewheeling voltage during the off cycle. During PWM mode the freewheeling voltage is kept low in order to decrease the energy level in the coil slowly, which results in a more economical PWM duty cycle. In the event of switching the coil finally off, the freewheeling voltage is switched to the maximum which results in a quick release of the energy stored in the coil, and the switch-off happens fast.


Safety Switch

The high-side safety-switch enables or disables the connection of the solenoid to the car battery. This intelligent switch is separate from the solenoid driver chip.



Temperature Sensor (TEMP)

The temperature sensor monitors the temperature of the chip area close to the low-side power driver stage.



Oscillator (OSC)

The 1 MHz on-chip oscillator provides the clock for the microprocessor and the control logic on the chip.



Analog-to-Digital Converters (ADC)

Depending on requirements Analog Digital Converters can be designed by using the standard core or additional modules for reduced noise, trimming devices or memory. Use of junction isolated devices makes the ADC design robust versus substrate noise.
Zener zaps and fuses are available for trimming of parameters like offset during wafer probing or final test. Several robust ADCs can be selected from X-FAB's analog standard cell library.




The microprocessor controls the PWM cycles of the solenoid, communicates via the SPI with other parts of the electronic control unit and is responsible for fail-safe functionality like monitoring processing watch dogs, over-voltage and over-temperature shutdown as well as monitoring the wiring and the proper function of the solenoid.
Different digital libraries optimized for speed, power and noise available in different technologies allow synthesizing microprocessor cores for X-FAB process technologies.



Non-Volatile Memory (NVM)

Embedded non-volatile memory stores microprocessor firmware and setup data. X-FAB offers a process dependent portfolio of embedded NVM IP like ROM, OTP, EEPROM, FLASH and NVRAM.



LS Control

This block controls the Gate of the low side power HV device according to the microprocessor output. Pre-driver HV devices with VDS,max appropriate to the VGS requirements of the power HV devices are available in all process technologies.



HS Control

This block controls the Gate of the high side freewheeling power device according to the microprocessor output and the target switch-off times of the solenoid. HV devices which are able to float between the voltage rails are available in X-FAB process technologies.