Milpitas, Calif. Intersil Corp. has entered the light sensor market with the launch of its new EL7900, a light-to-current optical sensor, that integrates a photodiode and a current amplifier on a single surface-mount chip. The new device offers both a power- and space savings for portable and handheld system designers.
The EL7900 operates in a wide range of lighting conditions from 1 lux to 10,000 lux. This information can be used to determine the amount of ambient light present, which allows automatic backlight or brightness control for backlit keyboards and LCD monitors. This allows any handheld device to decrease the overall system power consumption by dynamically controlling the current sent to the display or backlight.
For example, a typical display will consume the same amount of power until a user changes the system settings, which is usually brightness control. By using the EL7900 ambient light sensor, a system can now detect changing conditions and automatically adjust the settings to keep the display at optimal brightness and reduce overall power usage, said the company. What's more, the EL7900 also consumes little power itself, and eliminates the need for an additional amplifier, typically required in a discrete photo resistor and/or photodiode solution.
The company said there are several key factors associated with ambient light sensors including the output current must be linear to the light intensity, and spectral wavelength sensitivity should be very close to the human eye. The EL7900 is designed to sense ambient light from 380 nm to 770 nm. The device’s output current is directly proportional to the light intensity on the integrated photodiode and the peak response of 540 nm is extremely close to the peak sensitivity of the human eye, according to the company.
Making the device easy to use, the EL7900 provides a simple current output that can be converted into a voltage with a single external resistor as compared to traditional light sensing applications that have used photodiodes in combination with complex signal conditioning circuits, said the company. As a result, it opens up many new possibilities in motion sensing, intrusion detection and other various medical or industrial sensing applications.
Intersil is also introducing the ISL29000, a low-power ambient light sensor suitable for portable applications. Although it consumes less current, the ISL29000 provides the same linear response and wavelength sensitivity as the EL7900.
Both the EL7900 and ISL29000 devices perform over a wide operating temperature of -40°C to 85°C. They also provide a 2.5 V to 5.5 V supply range and offer a low supply current of 1μA. Click here for the EL7900 datasheet.
The EL7900 is available now in a 5-pin ODFN package with a lead-free, RoHS-compliant finish. Suggested pricing is $0.70 each in quantities of 1,000.
Intersil Corp., 1-888-468-3774, www.intersil.com/display