SBBS002B January 1994 – June 2015 OPT101
PRODUCTION DATA.
The OPT101 is tested with a light source that uniformly illuminates the full area of the integrated circuit, including the op amp. Although the silicon of integrated circuit (IC) amplifiers is light-sensitive to some degree, the OPT101 op amp circuitry is designed to minimize this effect. Sensitive junctions are shielded with metal, and the photodiode area is very large relative to the op amp input circuitry.
If the light source is focused to a small area, be sure that it is properly aimed to fall on the photodiode. A narrowly-focused beam falling only on the photodiode provides improved settling times compared to a source that uniformly illuminates the full area of the die. If a narrowly-focused light source misses the photodiode area and falls only on the op amp circuitry, the OPT101 does not perform properly. The large 0.09-in × 0.09-in (2.29 mm × 2.29 mm) photodiode area allows easy positioning of narrowly-focused light sources. The photodiode area is easily visible because the area appears very dark compared to the surrounding active circuitry.
The incident angle of the light source also effects the apparent sensitivity in uniform irradiance. For small incident angles, the loss in sensitivity is simply due to the smaller effective light gathering area of the photodiode (proportional to the cosine of the angle). At a greater incident angle, light is diffracted and scattered by the package. These effects are shown in Figure 5.