For DC-to-DC (DC/DC) powered LED lighting applications, discussions can be based on different power ranges. 1) 1~3W DC/DC LED step-down application Typical 1 to 3W DC/DC LED step-down lighting applications include MR11/MR16, automotive lighting, solar power, and more. These applications feature input voltages from 5 to 28 Vdc, support for 350mA and 700mA constant current output, frequency up to 500kHz to 2MHz, energy efficiency of no less than 90%, and an operating temperature range of -40°C to 125°C. In this type of application, ON Semiconductor's CAT4201 step-down LED driver can be used . The device's patented switch-control architecture drives up to seven LEDs in series (at 24V input) with up to 94% efficiency and provides protection features such as LED open-circuit protection, current limiting and thermal protection. Figure 1: CAT4201 1~3W DC/DC LED scheme. 2) 1~30W DC/DC LED step-down application Typical 1 to 30W DC/DC LED step-down applications include MR16 spotlights, secondary side DC/DC LED drivers in street lighting. In this type of application, the input voltage range is 7 to 120 Vdc, the output voltage range is 6 to 110 Vdc, and the 350mA, 700mA or 1A constant current output is supported, with an energy efficiency of at least 90%. This type of application can use ON Semiconductor's NCL30100 buck LED driver. This device's external switching MOSFET provides flexible input voltage and output current design with energy efficiency greater than 95%. See Figure 2 for the application circuit diagram. Figure 2: NHL30010 based 1-30W LED step-down application and NCP3066 based 3-20W LED boost application.
Metal Film Resistor is Film resistor (Film Resistors) of a kind.It is the high temperature vacuum coating technology will be closely attached to the porcelain nickel chromium alloy or similar bar surface skin membrane, after debugging cutting resistance, in order to achieve the final requirements precision resistance, then add appropriate joint cutting, and on its surface coated with epoxy resin sealing protection.As it is a lead resistance, it is convenient for manual installation and maintenance, and is used in most household appliances, communications, instruments and instruments.
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