On Semi公司的NCL30051是峰值电流控制固定关断时间的降压控制器,适合用于LED驱动器应用,可调整关断时间,源250mA/沉500mA峰值驱动能力, 25°C时的电流检测精度±3.2%,3.3V电平调光输入,具有热关断,过流保护和最大开态时间保护,主要用于LCD屏的LED背光驱动器,LED条灯,LED街灯和LED灯泡.本文介绍了NCL30051主要特性,方框图, 典型应用电路图, 输入80V 350mA输出的降压LED驱动器评估板NCL30105GEVB电路图,材料清单和PCB布局图.
The NCL30105 is a peak current controlled fixed off time buck controller designed for LED driver applications. It is optimized to operate in deep continuous conduction mode ELiminating the need for output electrolytic capacitors. Featuring an adjustable off time generator, the controller can drive a MOSFET up to a switching frequency of 500 kHz. A dedicated dimming pin enables the use of a pulsewidth modulated logic signal to dim the LED directly. The soft-start pin creates a startup sequence that slowly ramps up the peak current and enables the adjustment of the peak current set point for analog dimming control. The device features robust protection features to detect switch overcurrent faults and to detect maximum on time events.
NCL30051主要特性:
• Constant Off Time Current−Mode Control Operation
• Adjustable Off Time (0.5 [1]s to 10 [1]s)
• Internal Leading Edge Blanking
• Source 250 mA / Sink 500 mA Peak Drive Capability
• ±3.2% Current Sense Accuracy at 25℃• Internal Startup Delay
• 3.3 V Logic Level Dimming Input
• This is a Pb−Free Device
NCL30051安全特性:
• Thermal Shutdown
• Maximum On Time Protection
• Overcurrent Protection
NCL30051典型应用:
• LED Backlight Drivers for LCD Panels
• LED Light Bars
• LED Street Lighting
• LED Bulbs
图1.NCL30051方框图
图2.NCL30051典型应用框图
图3.NCL30051典型应用电路图
图4. 评估板NCL30105GEVB外形图:输入高达80V,输出350mA
图5. 评估板NCL30105GEVB电路图(1)
图6. 评估板NCL30105GEVB电路图(2)
评估板NCL30105GEVB材料清单:
图7. 评估板NCL30105GEVB元件布局图:顶层
图8. 评估板NCL30105GEVB元件布局图:底层
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