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A New Approach to Circuit Breaker Design Using Silicon Carbide Switches - Nov 21
Mechanical circuit breakers can be low cost with minimal losses, but they operate slowly and wear out. Solid state versions overcome the problems and are becoming increasing viable as replacements at...
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Power Electronics Europe News
 
Automotive buck-boost drivers meet white LED trend

Using three to four white LEDs in a single string powered from 12 V battery input is desirable for many automotive lighting uses. Addressing this market trend, used in fog, back up, daylight running lamps (DRLs), side mirrors and other automotive lighting applications, the high switching regulator provides 2.0MHz operation, enhanced performance in PWM dimming capability and fault protection, reducing the external component count, claims the company.

 

It can be operated in buck mode up to 2.0A, to drive one or two white LEDs from the battery, or up to 12 white LEDs from a pre-boost supply.

 

The high-frequency switching regulator provides constant output current to drive high-power LEDs. It is designed to aid in EMC/EMI design by frequency dithering, soft freewheel diode turn-off, and well controlled switch node slew rates. A programmable oscillator allows the device to switch up to 2.5MHz, outside EMI-sensitive frequency bands, such as the AM band. It integrates a power MOSFET for step-down (buck) or inverting buck-boost conversion. The 50V-rated enable pin can be tied to Vin for automatic startup, to support battery-level PWM dimming common in legacy body controllers. The input range is from 3.8 to 50V.

Current-mode control and simple external compensation enable the device to achieve fast transient response. The control loop is designed for PWM dimming operation to achieve low dimming on-time, low turn-on overshoot, accurate PWM duty cycle, and wide dimming range.

Protection features include pulse-by pulse current limit, hiccup mode short-circuit protection, open/short freewheeling diode protection, boot open/short voltage protection, Vin under-voltage lockout, and thermal shutdown.

The AEC-Q100 automotive-qualified driver is available in a small 10 pin DFN package with thermal pad and wettable flank.

 

 



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