Monolithic Optical Proximity and Digital Ambient Light Sensor ICs from ROHM Semiconductor

The new sensor ICs are able to drive three peripheral infrared LEDs through an integrated LED driver in the proximity sensor block. A receiver block in the sensor IC detects the light reflected from people or objects and analyzes the phase difference. Designers just have to connect the IC to the host system to screen movement a couple of cm above the sensor IC.

Integrated ambient light sensor block suitable for backlight dimming

The BH1771GLC's built-in ambient light sensor reduces power consumption in devices equipped with an LCD in a variety of environments by controlling the backlight brightness based on ambient conditions. In addition, in order to prevent malfunctions during conversation or key operation (i.e. when the user's face/a finger is nearby) a proximity sensor is integrated that detects objects and prevents corresponding operations. Also, the backlights are turned off during this time in order to reduce power consumption. ROHM provides both dimming and malfunction prevention capability on a single chip.

The ambient light sensor features spectral sensitivity characteristics close to the human eye, resulting in stable high sensitivity, regardless of light source (i.e. incandescent, fluorescent, sunlight). The result is optimum performance and visibility in a variety of environments.

In order to increase operation time especially of battery-driven portable devices, the internal components must deliver added functionality. Meeting this requirement, the ambient light sensor and proximity sensor blocks of the BH1771GLC family feature intermittent operation that further reduces power consumption.

Key Features

* Shutdown, measurement interval and proximity detection sensitivity set via I2C
* Compact 2.8 x 2.8 x 0.9mm package: WLGA010V28

Proximity sensor block

* Touchless motion detection function
* Digital 8bit output (I2C)
* Detection distance: 10 - 100mm (set via I2C)
* IrLED current driver built in
* Integrated sunlight cancelling circuit
* Measurement interval range: 10ms - 2000ms
ALS

* Digital 16bit output
* Reduced sensitivity variation (±15%)
* Measurement interval can be set between 100ms and 2000ms