The A6271 is a new DC-DC converter controller that provides a programmable constant current output to drive high-power series LEDs. The controller is based on a programmable fixed-frequency, peak-current-mode control architecture. DC-DC converters can be set up in a variety of different switch configurations, including boost, buck, SEPIC, and buck (ground reference switch).
The A6271 provides an extremely cost-effective solution with an external logic-level MOSFET and minimal external components. The maximum LED current can be set using a separate external detector resistor and can be precisely adjusted using a current reference input (analog control). External PWM dimming is possible via PWMIN input, and it also provides a shutdown mode. As an alternative, the PWMIN and DR pins can be programmed to use the internal PWM dimming circuitry. The PWMOUT output can be controlled by either PWM scheme, which drives an external p-channel MOSFET that connects the LED string in series. The MOSFET also isolates the load in certain fault conditions, including output-to-ground shorts.
The A6271 has been engineered to minimize electromagnetic emissions through distributed decoupling and externally programmable frequency jitter circuitry (configured as required by the EMI Specification CISPR 25). It can also set the basic switching frequency below 150 kHz, as required by most EMI standards.
The A6271 has comprehensive integrated protection to prevent failures in ICs, LED driver systems, and LED strings. Even if a single point of fault occurs in the programmable output overvoltage protection circuit, the fixed output overvoltage protection ensures that the maximum voltage rating is not exceeded. Other protection features include: LED overload (boost, SEPIC), output undervoltage (buck or buck), input supply (VIN) undervoltage, 5 V regulator (VREG) output undervoltage, high-side power supply (PWM PMOS) undervoltage, and thermal protection.
apply
-
车用高功率 LED 照明系统
-
雾灯、倒车灯、日间行车灯 (DRL)、示廓灯和前大灯。
-
-
符合汽车业的《AEC – Q100 标准》
-
恒流 LED 驱动
-
4.5 V - 50 V 电源
-
LED 灯串最大电压 53.3 V
-
升压、升降压、SEPIC 和降压开关转换器
-
70 kHz - 700 kHz 可编程开关频率
-
PWM 控制的 PMOS 驱动器可驱动 LED
-
低工作循环时的电流控制
-
通过外部 PWM、内部 PWM 和/或模拟调光功能调光
-
频率抖动方案能有效扩展频谱以减少电磁干扰
-
全面的故障防护与故障标记功能