Standalone Evaluation Platform for TI Light Sensors
Abstract
Electronic devices that use light sensors are becoming more prevalent in applications such as smart watches, laptops, TVs, automotive displays, and video surveillance cameras. TI's light sensor portfolio includes devices to measure photopic, broad, and light color spectrums. A standalone evaluation test is needed to make sure that the light sensors are working as expected before being mounted on a board (flex or non-flex PCB) for production use. TI's standalone test platform evaluates light sensors without external computers or hardware. Optionally, custom evaluation platforms are another method to test. This application note describes how to build a standalone evaluation test, including material inspection, hardware design considerations, and the assembly of test platforms.
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1 Introduction to TI's Light Sensor Portfolio
A light sensor is a device that outputs a signal that is proportional to the amount of light incident upon the sensor area. In many industrial, automotive, and personal electronic display applications, the light sensor is placed behind a dark glass window or around a display to sense ambient light.
TI's light sensor portfolio has several light sensors that fit various applications. Some popular sensors are the OPT3004, OPT3007, and OPT4001. TI light sensors are available in three package options: USON-6, SOT-8, and PicoStar™. USON-6 and SOT-8 are top-facing packages with the sensor and pins on opposite sides of the package. The USON-6 and SOT-8 packages are available for the OPT3004 and OPT4001. The PicoStar package is bottom-facing, with the sensor and pins on the same side. Bottom-facing sensors require a hole cut through the flex PCB to allow light through. For more information on bottom-facing light sensors see also the System design for bottom facing light sensors video. The PicoStar is significantly smaller than the top-facing packages and is available for the OPT3007 and OPT4001. The package shown in Figure 1-1 is a top-facing SOT-8 package, and the package shown in Figure 1-2 illustrates the sensor position of the bottom-facing PicoStar package.
Figure 1-1 Sensor Position of the SOT-8
Package
Figure 1-2 Sensor Position of the PicoStar™ PackageThe USON-6 is an unleaded 6-pin package, while the SOT-8 is a leaded 8-pin device that operates like the USON-6 package by using only 6 pins. The two unused pins are no-connect. In contrast, the PicoStar is a 6-pin package that uses only 4 pins to operate. The address and interrupt pins are removed to accommodate a large sensor area hole on the package bottom.
