Semtech SC446高效多串WLED驱动方案
Semtech公司的SC446是集成了升压转换器的高效多串W器,输入电压从4.5V到27V,最大输出电压36V,内部功率开关为2.5A,能驱动3串多达30个W,每串电流100mA,串与串的电流匹配典型值为2%,整体效率大于90%,主要用在中型LCD屏,笔记本电脑显示,汽车导航显示和手提媒体播放器.本文主要介绍SC446主要特性和典型应用电路.
The SC446 is a high-efficiency multiple string WLED driver with an integrated boost converter. It operates over a wide input range from 4.5V to 27V with a maximum out- put voltage of 36V and a 2.5A internal power switch. It can drive up to thirty WLEDs in 3 strings with current up to 100mA per string. The string-to-string current matching is 2% typical, 3% maximum. The overall efficiency is greater than 90% due to the low current sense voltage and a low-impedance internal power switch. The wide PWM dimming range boasts a ratio of 500: 1.
The 700kHz switching frequency enables the user to optimize the external component sizes for efficiency. When there are fewer than 10 LEDs in each string, users can ad-just the output voltage protection yiding an allowable
reduction in associated costs, size and voltage ratings of the output capacitor.
The SC446 also features comprehensive open and short- circuit LED protection functions. It disables the corresponding strings with LED open or LED short conditions while maintaining normal operation of other, unaffected LED strings. This feature allows LCD panels to remain viewable even under LED failure, wire disconnect, or short-circuit conditions. The internal thermal shutdown protects the IC from overheating at abnormal conditions.
The SC446 is available in a thermally-enhanced TSSOP-16 EDP package.
SC446主要特性:
Wide input voltage range from 4.5V to 27V
36V maximum output voltage
Drives up to 30 WLEDs in 3 strings
Programmable LED current for up to 100mA per string
+/- 2% string-to-string current matching
Up to 90% eciency
Wide 0.2% to 100% PWM dimming range
Possible analog dimming
Integrated 2.5A power switch
700kHz switching frequency for small size
Adjustable OVP for cost-e!ective output cap selection
Open/short LED protection
Thermal protection with auto-recovery
Thermally enhanced TSSOP-16 EDP package Pb Free, Halogen Free, andWEEE/RoHS Compliant
SC446应用:
Medium-sized LCD panel
Notebook Display
Automotive Car Navigation Display
Sub-Notebook and Tablet Computer Displays
Portable Media Players
图1.SC446典型应用电路
详情请见:
http://www.semtech.com/images/datasheet/sc446.pdf
The SC446 is a high-efficiency multiple string WLED driver with an integrated boost converter. It operates over a wide input range from 4.5V to 27V with a maximum out- put voltage of 36V and a 2.5A internal power switch. It can drive up to thirty WLEDs in 3 strings with current up to 100mA per string. The string-to-string current matching is 2% typical, 3% maximum. The overall efficiency is greater than 90% due to the low current sense voltage and a low-impedance internal power switch. The wide PWM dimming range boasts a ratio of 500: 1.
The 700kHz switching frequency enables the user to optimize the external component sizes for efficiency. When there are fewer than 10 LEDs in each string, users can ad-just the output voltage protection yiding an allowable
reduction in associated costs, size and voltage ratings of the output capacitor.
The SC446 also features comprehensive open and short- circuit LED protection functions. It disables the corresponding strings with LED open or LED short conditions while maintaining normal operation of other, unaffected LED strings. This feature allows LCD panels to remain viewable even under LED failure, wire disconnect, or short-circuit conditions. The internal thermal shutdown protects the IC from overheating at abnormal conditions.
The SC446 is available in a thermally-enhanced TSSOP-16 EDP package.
SC446主要特性:
Wide input voltage range from 4.5V to 27V
36V maximum output voltage
Drives up to 30 WLEDs in 3 strings
Programmable LED current for up to 100mA per string
+/- 2% string-to-string current matching
Up to 90% eciency
Wide 0.2% to 100% PWM dimming range
Possible analog dimming
Integrated 2.5A power switch
700kHz switching frequency for small size
Adjustable OVP for cost-e!ective output cap selection
Open/short LED protection
Thermal protection with auto-recovery
Thermally enhanced TSSOP-16 EDP package Pb Free, Halogen Free, andWEEE/RoHS Compliant
SC446应用:
Medium-sized LCD panel
Notebook Display
Automotive Car Navigation Display
Sub-Notebook and Tablet Computer Displays
Portable Media Players
图1.SC446典型应用电路
详情请见:
http://www.semtech.com/images/datasheet/sc446.pdf
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