The JSA-1212 integrates an ambient light sensor (ALS), a proximity sensor (PXS), an infrared emitting diode (IRED) driver and an SMBus compatible I2C Interface into one chip. The ALS and PXS work independently, and communication to the device is accomplished through the fast I2C interface (up to 750 kHz) for easy connection to a microcontroller or embedded controller. A flexible interrupt scheme is provided for minimal microcontroller utilization. The ambient light sensor (ALS) has 5 working ranges for adapting to different applications and various opto-mechanisms. The ALS reading (output data) is proportional to the ambient light; not extra data manipulation is required. It also has a built-in circuit to reject the 50Hz/60Hz flicker noise caused by indoor light sources. The most distinguished feature of the ALS is that the spectral response is almost the same as human eye's photopic vision due to a well-engineered optical coating on the top of the ambient light detector; thus, light source correction coefficient is not necessary.
| The proximity sensor (PXS) employs a narrow-band, multi-layer optical coating to suppress most infrared background. Synchronized with the built-in IRED driver, the proximity sensing circuitry adopts track-and-hold (T&H) and correlated double sampling (CDS) techniques to reject non-synchronized infrared signals and electrical DC offset. Each proximity measurement takes about 0.8mS, and various sleep-time in between can be programmed through I2C interface to reduce overall power consumption. The JSA-1212 provides a separate pin for level-style interrupt which simplifies and improves system efficiency by eliminating the need to poll a sensor for an ALS or PXS readings. An interrupt is generated when the reading of an ALS or PXS exceeds either an upper or lower threshold. In addition, a programmable interrupt persistence feature allows the user to determine how many consecutive exceeded readings are necessary to trigger an interrupt. Interrupt thresholds and persistence settings are configurable through I2C interface. |
| Application |
| - Display and keypad dimming adjustment and proximity sensing for: |
| > Mobile Devices: smart phone, PDA, GPS. > Computing Devices: laptop PC, notebook. > Consumer Devices: LCD-TV, digital picture frame, digital camera. |
| - Industrial and medical light and proximity sensing. |
DIMENSIONS: in mm
Pin Description
Spectral Response
Absolute Maximum Ratings
Electrical Characteristics (VDD = 3.0V, TA = +25°C, REXT = 499kΩ 1% tolerance.)
