epc110
Design Precautions: EMC shielding
The sensitivity at pin PD is very high in order to achieve a long operation range of light barriers even without
lenses in front of the IR LED and/or the photo diode. Thus, the pin PD is very sensitive to EMI. Special care
should be taken to keep the PCB track at pin PD as short as possible (a few mm only!). This track should be
kept away from the IR LED signal tracks and from other sources which may induce unwanted signals. It is
strongly recommended to cover the chip, the photodiode and all passive components around the chip with a
metal shield. A recommended part is shown in Figure 22. The pins at the bottom are to solder the shield to
the PCB with electrical connection to GND. The hole in the front is the opening window for the photo diode.
The backside of the PCB below the sensitive area (PD, epc110) shall be a polygon connected to GND to
shield the circuit from the backside as well.
Figure 22: Recommended EMC
shield
Ambient Light
Photodiode DC current can be generated by ambient light, e.g. sunlight. DC current at pin PD does not generate a DC output signal. However,
if IPDDC is above the stated maximal value, the input is saturated. This blocks the detection of AC current pulses.
Photodiode Capacitance
If the photo diode capacity is above the specified value, a lower detection sensitivity and a possible higher sensitivity spread results.
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
23
Datasheet epc110 - V2.1
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EPC [ ESPROS PHOTONICS CORP ]
