Integrated Light Sensor Exceeds 15 Years of Lifetime

Melexis adds light-to-voltage sensor to the SensorEyeCTM series. Melexis announces the launch of the MLX75305 Light-to-Voltage SensorEyeCTM. This is the second member of the SensorEyeCTM series of optical sensors specifically designed for high volume automotive, industrial and consumer applications. The light sensor’s output gives a voltage that varies linearly with incident light.

This MLX75305 is an integrated sensor IC, which means that the photodiode, transimpedance amplifier and linear voltage output stage are all included in the sensor chip. This guarantees stable light responsivity over time and over temperature, and also drastically improves noise behavior when compared to designs that use discrete photodiodes. It simplifies application design, requires fewer external components and improves quality.

The first SensorEyeCTM device - the dirt-robust MLX75303 Optical Switch - was launched in April 2008.

More than 15 Years of Lifetime
Melexis did not wait 15 years before bringing this light sensor to the market. Instead, SensorEyeCTM devices are baked in an oven at 150°C and remain powered-on during a total test run time of more than 500 hours. This test accelerates the aging process of the silicon by a factor of 258 for sensor operations at 55°C, resulting in an equivalent continuous operating lifetime of more than 132000 hours.

Because all sensors performed well after the aging test, their lifetime thus exceeds 15 years.

SensorEyeC series
“The high temperature operating lifetime (HTOL) testing is one of many qualification tests we do on our light sensors,” says Sam Maddalena, Business Unit Manager Opto Sensors. Maddalena continues, “Our automotive customers request this kind of reliability evaluation because repairing defects in cars is very expensive and inconvenient for car owners. Our customers will benefit tremendously from the low PPM, temperature independency of the sensor’s behavior and the 260°C solder reflow capabilities.”

The MLX75305 is suited for measuring ambient light or for controlling LED light in LCD backlight dimming applications. Its unique features include:

• Highly linear voltage output
• Light responsivity that is relatively independent of temperature
• Small DFN open cavity package: 3mm x 3mm x 0.65mm (also available in SO8 package)
• Very high positional accuracy: the small, symmetrical DFN package provides pin-to-photodiode accuracy better than ±85µm.
• Extended operating temperature range of -40°C to +125°C that meets AEC-Q100 automotive specifications. A consumer version up to +85°C is available also.
• Lead free solder reflow compatible for 260°C peak process temperatures

Applications

The MLX75305 Light-to-Voltage SensorEyeCTM is perfectly fit for a number of applications:

• LCD backlight dimming of television sets, notebook computers, mobile phones (GSM), GPS receivers and portable multimedia players (MP3, DVD). This enables easier screen reading and helps save battery power on portable devices.
• Hand presence detection. For instance for automatic activation of water taps and hand dryers.
• LED lighting: LED monitoring and control of light intensity & colour.
• Automotive applications include automatic light dimming of instrument panels and displays, headlights on/off control and hand presence detection for opening doors.