How designers choose inductors for LED circuits

One product we are familiar with as consumers is the traditional incandescent flashlight, which usually has a very basic circuit design: a battery, an incandescent light bulb, an on/off switch, and a way to connect all of these things. In contrast, a new type of LED flashlight that appears on store shelves now presents a much larger electronic complexity. They use a variety of drive circuits with a variety of components. It's easy to imagine that flashlight designers always need a wealth of expertise to produce rugged and durable things for sports and police, fire and rescue applications. However, they do not necessarily have experience with DC-DC converters, let alone components such as power inductors that make up a typical DC-DC converter bill of materials.

As the range of new LED lighting applications grows, it is easy to imagine the re-enactment of various lighting products. Helping these new industries apply their existing DC-DC converter expertise in their designs to determine the responsibility of power component manufacturers – the way to do this is to achieve performance and energy efficiency with new lighting applications. . This article explores how an experienced engineer can quickly and easily take advantage of existing DC-DC converter expertise, including the details of magnetic components.

Coilcraft has developed several tools to guide users through the selection of inductors. These tools are already available at the new LED Design Center. These tools have been arranged to give users a starting point for a choice.


Starting with the driver IC

The list of LED driver ICs is long, including all famous brands such as Allegro Micro, Austria Microsystems, Durel, Fairchild, Freescale, Linear Technology, Maxim, National Semiconductor, NXP, ON Semiconductor, STMicroelectronics and Texas Instruments . Documents from IC companies usually include not only the technical specifications of their products, but also design examples and application tips. A complete, ready-to-use evaluation or demonstration kit is often available.

In addition to common reference design information, these companies have created special LED design centers as a way to centralize information about specific lighting applications. For example, National Semiconductor offers the online WEBENCH LED Designer as part of its well-known WEBENCH Designer tool. The Texas Instruments website provides power management products with LED driver, lighting and display solutions, and Linear Technology lists an LED driver IC page. It is these examples of driver IC manufacturers that support the fledgling LED lighting market.

The Coilcraft LED Design Center collects information about LED driver ICs and helps users select the appropriate inductors using the inductor matching tool. This tool helps users choose from an integrated circuit company, driver ICs, and a list of specific applications of interest. With the information selected, the tool provides the appropriate inductor information for the application. Since the inductor listed as a solution is a real-time database from a dynamic component model, this tool is more powerful than a simple inductor cross-reference list listed in the integrated circuit reference design. This feature provides the user with a list of available inductors that are always up to date, not limited to those defined by the reference design at the time of publication.


Starting with LED

As the center of the application, the characteristics and operational requirements of the LED device itself must be the starting point for most designs. For example, some basic operating parameters are easily found in the LED data sheet.

Most websites from these manufacturers offer a variety of useful application guides, including a list of technology partners to facilitate integration in different areas of expertise.

From the choice of driver topology, using the LED specifications provided by the manufacturer, and depending on the available input voltage and the number of LEDs driven, engineers may want to specify the driver topology: buck, boost, buck-boost Type or SEPIC. The Coilcraft LED Design Center quickly determines the right inductor for each topology.

For example, this tool can be used to select a coupled inductor for a SEPIC converter to drive a white LED, as shown in Table 1. Typically these white LEDs are specified to drive a forward current of 350mA, which can be powered by a Li-Ion battery, a typical power supply for handheld devices.


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Description of wireless touch dimmer

Input(V): DC12V/24V

Color: Black

Material: Plastic

Battery: LR03(AAA)/CR2477

Warranty: 3 years

Wirelss: 2.4G

Wireless Communication Distance: 6m

Size: 46*49*14.5mm

Name: LED Touch Dimmer Switch

Wireless Touch Dimmer

 

Wireless Touch Dimmer

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