Det bliver nu markant lettere at opbygge komplekse LED matrix designs

Linear Technology præsenterer 8-switch matrix LED dimmer, der simplificerer opbygningen af komplekse LED matrix designs (in english).

New matrix LED configurations are emerging in automotive and industrial High Brightness (HB) LED applications. In the new automotive applications, the combination of turning on, turning off and dimming LEDs within the matrix combined with different reflectors within the light assembly, enable the light beam to be modified to reduce glare for oncoming traffic or to 'steer' the beam to better illuminate corners.

This adaptable beam operates in conjunction with cameras to offer the required feedback about the surroundings of the vehicle. In order to independently turn-on, turn-off or dim individual LED sectors within the matrix, a matrix LED dimmer is required which works in conjunction with a constant current LED driver.

The matrix dimmer must be digitally controlled with a common digital bus, such as I2C. For larger matrix displays, multiple matrix dimmers may be required to operate from a common I2C bus. High efficiency is of paramount importance as it minimizes thermal design considerations. To maximize reliability both the HB LED driver ICs and the matrix dimmer must offer robust protection of both open and shorted LED conditions. 

A new direction

Linear Technology  announces the LT3965, a LED bypass switching device that enables independent dimming and diagnostics of eight individual LEDs or LED segments. The LT3965 works in conjunction with a LED driver circuit configured as a current source. It features eight individually controlled floating 17V/330mΩ NMOS switches .

Using these internal power switches and an integrated I2C serial interface, individual LEDs within the string can be turned on or off, or they can be PWM dimmed to offer unique patterns within the LED matrix. 

Typical applications include automotive matrix LED headlights, industrial lighting and large LED display lighting. The I2C serial interface enables digital programming with 256:1 dimming ratios with or without the 11-bit resolution fade transition between the dimming states.

Each switch can control and monitor a single LED or a segment of up to 16V of series-connected LEDs. The LT3965’s 8V to 60V input voltage range can accommodate a wide range of LED drivers commonly used in automotive and industrial applications. For larger LED matrix applications, multiple LT3965s (up to 16) can use a common I2C bus. 

The LT3965’s eight switches can be connected in parallel and/or in series to bypass current around one or more LEDs in a string. When multiple LT3965s are used, the I2C serial interface enables communication between the master microcontroller and one or more LT3965s configured as slaves.

The LT3965 provides an internal clock generator and also supports an external clock source for PWM dimming. Additionally, each channel of the LT3965 offers both open LED and shorted LED fault reporting and protection. It is offered in a 28-lead TSSOP thermally enhanced package, ensuring a compact solution footprint for matrix dimming applications. 

The LT3965EFE is available from stock an industrial temperature version. The LT3965IFE is tested and guaranteed to operate from a –40°C to 125°C operating junction temperature range.

http://www.linear.com/product/LT3965. See the LT3965 video at http://lt.linear.com/wp