Vision and Imaging Sensors / Detectors
Digital Ambient Light Sensor works with I2C bus Hs mode.
Press Release Summary:
Responding to demand for accelerated internal transmission speeds in mobile phones, BH1780GLI digital brightness sensor IC supports the I²C bus Hs (High-speed) mode for optimized internal signal transfer rate of 3.4 Mbps. Integral ADC offers 0-65,535 lux output range (1 lux increments) for measuring ambient light, and spectral sensitivity characteristics are similar to human eye. Other features include 50/60 Hz optical noise elimination function and ±20% sensitivity variation.
Original Press Release:
The First Digital Ambient Light Sensor Compatible with I2C Bus Hs Mode
ROHM Co., Ltd., in response to market demand for faster internal transmission speeds in mobile phones to keep pace with increasing functionality, has announced the development of a digital brightness sensor IC that supports the new I2C bus Hs (High-speed) mode - an industry first. Internal signal transfer rates are increased by up to 8.5 times over the conventional Fast mode. This development is expected to trigger widespread use mobile phones while enabling even greater functionality.
Minimizing LCD backlight power in mobile phones is becoming an increasingly important consideration, especially given the continual progression towards greater functionality. Many devices now implement some type of brightness control, normally by utilizing a microcontroller and LED driver along with an ambient light sensor. However, this requires relatively fast bus speed, making the current I2C bus transmission mode (Fast), with a transmission speed of only 400Kbits/s, a potential obstacle to increased performance and functionality in future smart phones.
The BH1780GLI answers this demand by supporting the new Hs mode that stipulates a transfer rate of 3.4Mbit/sec. Additional features include a high-precision A/D converter with a wide output range (0-65,535 lux, in 1 lux incremenents) for measuring ambient light from darkness to direct sunlight, along with spectral sensitivity characteristics similar to the human eye that is stable across different light sources (i.e. incandescent/fluorescent lamps, sunlight). A noise elimination function is also built in for reliable operation regardless of power source fluctuations (e.g. AC oscillation). In addition, unique laser trimming technology limits sensitivity variations to ±20%.
Key Features
1. Supports I2C bus Hs mode (max. 3.4Mbit/s)
2. Brightness level output digitally (0 to 65,535 lux)
3. 50Hz/60Hz optical noise elimination function ensures stable brightness measurement
4. Sensitivity variation: ±20%
5. UV-blocking resin package eliminates adverse effects from UV light
Specifications
Part No. Output Type Source Voltage Sensitivity Variation Brightness Measurement Range Operating Temperature Range Package Type Dimensions
(V) (%) (lx) (ºC)
BH1780GLI Serial 16bit 2.3 to 3.0 ±20 0 to 65535 -40 to +85 WLGA04IW02 2.0x2.0
h=0.8 max
Terminology
I2C stands for Inter-Integrated Circuit - a type of serial bus developed by Philips designed for connecting low-speed peripheral devices to the mainboard. It is widely used in a number of electronic devices, including mobile phones. Different modes exist, based on the bitrate: Standard mode, Fast mode, and high-speed (Hs) mode.
