Freescale Introduces Third-Generation eXtreme Switch For Automotive Lighting
Freescale Semiconductor has introduced the third generation of its eXtreme Switch portfolio with four high-side power switches – the first devices in the portfolio tailored for automotive lighting applications. The company states that the switches’ features, including the ability to drive high-intensity discharge (HID) xenon, halogen and light-emitting diode (LED) light sources with a single device, are engineered to allow automakers to improve lighting efficiency, extend bulb life and reduce bill of material costs. The devices are also said to be designed to provide greater power management flexibility than other, more conventional products on the market today.
The eXtreme Switch Gen III models are N-channel MOSFET switches with extremely low on-resistance, ranging from 10 to 35mΩ per channel that can simultaneously control the high sides of up to four light sources. The devices’ ability to accommodate multiple types of light sources is said to enable vehicle manufacturers to employ a single common body module design throughout its vehicle lineup.
According to the company, today’s vehicles employ more types of light sources than ever before, ranging from halogen to xenon and LEDs. Each type has unique power requirements that vary during the different stages of its operation. Conventional switch solutions that employ electromechanical relays and fuses can perform only rudimentary functions, and cannot provide system diagnostics and fault reporting. Freescale’s advanced eXtreme Switch devices are designed to eliminate these deficiencies by integrating the essential features required for optimum operation into a single integrated circuit (IC).
The devices use performance profiles for each type of light source to precisely track its operation and deliver optimal efficiency and greatest protection. For example, a halogen lamp draws high levels of current when first turned on, but much less once it has stabilized. The ICs allow the lamps to draw high levels of current when needed at turn-on but less during operation. This technique makes it possible to accurately track the current drawn by the light source in the critical turn-on phase and quickly detect a potential overcurrent or short-circuit condition and turn off the lamp before failure occurs. This light source profile optimization allows automakers to reduce wire size (gauge), which can lower the overall weight and cost of the wiring harness.
The eXtreme Switch devices’ performance extends to applications where the light source is dimmed using a pulse width modulation (PWM) technique that varies the average power to the bulb to control the light intensity. The devices use a flexible PWM capability that tailors the PWM signal during load turn-on and turn-off, extending the bulb life while providing full protection features.
The eXtreme Switch Gen III models provide diagnostics for the switch, light source and wiring harness, as well as comprehensive fault management and control of the loads without complex software. The devices use latched overcurrent shutdown protection. This technique is said to be preferable to the current limit method because it minimizes the thermal stress within the device during an over-load condition, greatly reducing the junction temperature rise and vastly improving reliability.
The four eXtreme Switches are sampling now, and full production is expected later this quarter.
