Allegro MicroSystems, LLC Announces New Automotive High Current LED Controller
May 12, 2015
Allegro MicroSystems, LLC Announces New Automotive High Current LED Controller
May 12, 2015
Designed with Upgraded Performance and Configuration Options
Worcester, MA– Allegro MicroSystems, LLC introduces a new DC-DC converter controller, providing a programmable constant current output for driving high power LEDs in series.Allegro’s A6271 controlleris based on a programmable fixed frequency, peak current mode control architecture. The DC-DC converter can be configured in a myriad of different switching configurations including boost, buck-boost, SEPIC and buck (ground referenced switch). This new device is designed for automotive exterior lighting applications to include high power LED lighting systems, fog lights, reversing lights, daytime running lights (DRLs), position lights, and headlights.
A6271使用外部逻辑电平MOSFET和最小额外的外部组件提供经济高效的解决方案。最大LED电流设定为单个外部检测电阻，可以使用电流参考输入（模拟控制）精确调制。通过PWMIN输入可以提供外部PWM调光，这也提供了关闭模式。作为替代方案，可以通过编程PWMIN和DR引脚来使用内部PWM调光电路。PWM方案控制PWMOUT输出，驱动与LED串串联连接的外部P沟道MOSFET。该MOSFET还用于在某些故障条件下隔离负载，包括输出短路到地。
The A6271 has been carefully designed to minimize electromagnetic emissions through distributed decoupling and an externally programmable frequency dither circuit configured for the EMI specification CISPR 25. It is also possible to program the fundamental switching frequency below 150 kHz where most EMI standards begin.
Allegro’s A6271 has a comprehensive set of integrated protection features to protect the IC, the LED driver system, and the LED string against faults. Fixed output over voltage protection ensures no maximum voltage rating violations even under a single point failure of the programmable output over voltage protection circuit. Other protection features include; LED over load (boost, SEPIC), output under voltage (buck or buck-boost), input supply (VIN) under voltage, 5 V Regulator (VREG) output under voltage, high side supply (PWM PMOS) under voltage, and thermal protection.
The A6271KLPTR-T is available in a 16-pin eTSSOP (suffix LP) package with exposed thermal pad for enhanced power dissipation.