Claimed to be the most compact infrared emitting diode (IRED) in the high-power class, the SFH 4770S from Osram Opto Semiconductors provides a typical high optical output of 1200mW from a 2.7x2.0x0.6mm package. The device's broad emission characteristics and low profile make it suited for facial recognition and eye-tracking systems in smartphones and tablets that can activate applications in response to eye blinking instead of the usual double-click.
The basis for the emitter is the Synios package itself, which Osram introduced some time ago for LEDs in the visible spectral range for automotive applications. The package is extremely compact and provides optimum light extraction. The SFH 4770S is the first component in which this package has been used for infrared emitters. Installed in the IRED is a 1mm2 emitter chip with an 850nm wavelength in which two emission centres are provided with the aid of nanostack technology, in which two emission centres are epitaxially stacked in one chip. Overall, the component delivers a typical optical output of 1200mW at a current of 1A with only one chip.
With a height of only 0.6 mm, the SFH 4770S has a lower profile than all IREDs previously available in its output class. This makes it extremely attractive for designs that call for broad homogeneous illumination in a limited space. This is particularly true for applications in mobile devices such as smartphones and tablets.
“The SFH 4770S takes up very little space,” said Chris Goeltner, Product Marketing Manager, Osram Opto Semiconductors. “Compared to the Oslon, previously our most compact high-power IRED, we have managed with Synios to reduce the footprint by almost one-third and the height by around one quarter.”
The emission angle of 120° ensures that the target area is evenly illuminated. Even with this emission characteristic, the SFH 4770S achieves a typical radiant intensity of 375mW per steradian (mW/sr) at 1A thanks to its high overall output. This makes the IRED suitable for facial recognition and eye-tracking systems because they need the user’s face to be brightly and uniformly illuminated.
The Synios package is also highly suitable for injecting light into external optics or light guides. Another important property for all applications is the excellent thermal stability of the SFH 4770S. Its thermal resistance is a maximum of 9K/W.
The Synios SFH 4770S is already available on request for first customer projects. Volume start-up is planned for the end of January 2016.