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First LED Driver to Eliminate the Need for an External Microcontroller or Switch-Mode Converter is Ideal for Automotive Lighting Applications

  SUNNYVALE, CA —Maxim Integrated Products (NASDAQ: MXIM) introduces the MAX16806 EEPROM-programmable, 350mA, high-voltage (40V) linear, high-brightness LED driver. This IC can be programmed through an I2C* interface to fold back the LED current if input voltage or LED temperature rises above the programmed threshold. Although a traditional architecture requires switch-mode converters to reduce power dissipation, the unique design of the MAX16806 LED driver manages total power dissipation in a lighting system, and thus eliminates the need for a switch-mode converter. Consequently, the MAX16806 reduces both cost and EMI concerns for powering high-brightness LEDs. The benefits of the Company's approach will be immediately noticed in a broad range of lighting applications such as automotive interior and exterior lighting.

Switching from Incandescent Lamps to LEDs Poses a New Problem for Auto Makers

The automotive industry is replacing the existing incandescent lamps with white LEDs for dome and map lights. This change is done to create a technologically advanced image for the new cars. The LEDs need to work with the existing control module unit, and this poses a new problem for auto makers. The present theater dimming signal operates at very low frequency and causes the LEDs to blink noticeably during dimming. To eliminate this effect, the LED driver used to require a microcontroller to create a new PWM signal.

Unique LED Driver Design:

1.) Eliminates the Need for External Controls

The novel architecture for the MAX16806 eliminates the need for a microcontroller's PWM signal, because an on-board 200Hz ramp generator allows analog control for PWM or theater dimming effect. The device's high-voltage (40V rated) DIM pin can also sync with up to a 2kHz external PWM signal. The fast turn-on/off times ensure a wide dimming range, while the wave-shaping circuitry minimizes EMI.

2.) Reduces Production Costs

The MAX16806 was also designed to simplify production and reduce manufacturing cost. This LED driver uses one value of a current-sense resistor in conjunction with EEPROM-programmable current-sense reference to set the LED current for all LED bins.

3.) Makes Them Versatile for Many Applications

LED brightness can be changed automatically, on-the-fly on this device, a feature that makes it especially versatile for demanding lighting applications that extend far beyond the automotive industry. Designers simply adjust the RGB LED current level dynamically through the I2C interface. This allows the creation of a wide range of colors for architectural or general lighting applications.

Integrated debounce circuitry supplies the necessary wetting current for a momentary switch. This feature makes the MAX16806 an ideal LED driver for automotive dome- or map-lighting applications. The device requires minimum external components to implement the LED driver circuit, making it a cost effective solution for many lighting applications.

The MAX16805, a companion product, has many of the same features as the MAX16806, but is offered for applications that do not need LED current thermal foldback or wetting current and debounce circuitry for a momentary switch.

Key Driver Specifications

The MAX16806 driver combines a low-voltage (204mV) current-sense reference with differential LED current sensing to provide load accuracy of ±3.5%. This current accuracy allows consistent brightness for all light assemblies. The device's low-dropout pass element (0.5V typical) and current-sense reference minimize power dissipation. Output voltage is rated to 39V and allows the MAX16806 to drive multiple LEDs in series. The driver has overtemperature and short-circuit protection, important safeguards for lighting applications.

The MAX16806/MAX16805 are rated for operation over the automotive temperature range (-40°C to +125°C). They are available in a thermally enhanced, surface-mount, 5mm x 5mm, 20-pin TQFN lead-free package rated at 2.67W power dissipation. Prices for the MAX16805 start at $1.42 and $1.49 for the MAX16806 (1000-up, FOB USA).

Jueves, 07 Septiembre, 2006 - 12:08
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