Renesas - Digital Ambient Illuminance Sensor with Industry-Leading Compact and Thin SON Package

The PH5551A2NA1 device is the company’s first entry into the market for ambient illuminance sensors and incorporates Renesas Electronics’ technology expertise accumulated in the development and commercialization of photo detector IC products for CD, DVD, and BD players, a product category where Renesas Electronics enjoys the top market share (Note 1) in the industry. The new device is designed to contribute to improved performance and reduced power consumption, for example by automatically adjusting display brightness for the best viewing experience.

The PH5551A2NA1 device is a digital ambient illuminance sensor that detects the brightness of ambient light and sends a corresponding signal to a device such as a microcontroller (MCU). By using the PH5551A2NA1 device, system manufacturers can develop more compact and precise automatic brightness adjustment or automatic on/off circuits for digital household appliances and electronics, mobile terminals and handsets, factory automation (FA) equipment, and lighting fixtures for both indoor and outdoor use.

Ambient illuminance sensors detect the brightness experienced by human beings and output a corresponding signal to an MCU. They are mainly used in digital devices equipped with displays to enable automatic brightness adjustment and automatic on/off control according to the level of ambient light and contribute to improved performance and reduced power consumption, for example by automatically adjusting display brightness for the best viewing experience. These sensors are employed in products that include digital household appliances and electronics, mobile terminals and handsets, factory automation equipment, and lighting fixtures, and the market for ambient illuminance sensors is expected to grow by about 20 percent annually from 2011 to 2013.

In the past, light sensors employing cadmium sulfide have been widely used for such applications, but now demand for silicon semiconductor ambient illuminance sensors is growing due to their reduced environmental impact.

Against this background, Renesas Electronics utilized its process technology, circuit technology, package technology, and manufacturing technology derived from its photo detector IC products for CD, DVD, and BD players to develop new products for the illuminance sensor market. The PH5551A2NA1 device contributes to improved performance, reduced power consumption, and greater compactness in brightness adjustment circuits for digital devices, mobile terminals and handsets, factory automation equipment, and lighting fixtures.

Key features of the PH5551A2NA1 device:

(1) Clear mold SON package among the smallest and thinnest in the industry

The PH5551A2NA1 device employs clear mold package design technology and manufacturing technology accumulated over many years by Renesas Electronics in the development and commercialization of photo detector IC products. Its clear mold SON package measures only 1.56 millimeter (mm) × 2.55 mm × 0.55 mm, among the smallest and thinnest in the industry. The gap between pins of 0.5 mm and SON package make it easy to achieve a high mounting density on the printed wiring board.

(2) Reduction to ±20 percent of sensitivity variation due to different light sources

An internal circuit performs calculations based on signals from multiple light receivers with different wavelength sensitivity characteristics, enabling a reduction to ±20 percent of sensitivity variation due to different light sources, such as fluorescent lamps, LEDs, and incandescent bulbs. This enables control that corresponds to the ambient brightness as perceived by human beings, regardless of the illumination environment.

(3) Enhanced flexibility when used in combination with an MCU

In digital signal output applications for ambient illuminance sensors, two I2C™ bus slave addresses (identification numbers) are typically assigned, so multiple illuminance sensors can be connected to a single MCU and their uses can be allocated as required.

The PH5551A2NA1 device incorporates an interrupt function that can output a signal to the master device, such as an MCU, when the brightness exceeds a preset threshold value. This eliminates the need for constant communication between the MCU and the sensor and reduces the processing load on the MCU.

Renesas Electronics will continue to develop and introduce to the market ambient illuminance sensor products that contribute to improved performance, reduced power consumption, and greater compactness in brightness adjustment circuits for products incorporating displays, such as digital household appliances and electronics, mobile terminals and handsets, and factory automation equipment, all of which are expected to see rapid market growth moving forward. The company considers the PH5551A2NA1 device to have a role to play in enhancing the compactness and illumination adjustment accuracy of such products.

(Note 1) Renesas Electronics estimate. The company has an approximately 80% share of the market for light receiver diode IC products for CD, DVD, and BD players (2010).