EPC120 EPC [Espros Photonics corp], EPC120 Datasheet - Page 6

• Manufacturer Part Number: EPC120
• Description: Fully integrated Light-Barrier Chips with 2-Wire Bus Interface
• Manufacturer: EPC [Espros Photonics corp]

3. System Concept
1 If the LED pulse current is rather high, i.e. 1 A, two separate bus wires for the LED supply current are needed. Please refer to Error:
In a system with several reflective light barrier beams, each individual light barrier contains an emitter and a receiver. They are located at the
same place. As a receiver acts a photodiode and as an emitter a LED. Both can be controlled by only one single epc120. In contrast to the
epc11x-family, which are also light barrier chips, the epc120 can be used in a large distributed system. The devices are synchronized over the
2-wire bus line, organized by one epc100 and a microcontroller.
Figure 4 shows a typical distributed light barrier setup with five elements. Each element consist of an epc120, an emitter (LED), a receiver
(photodiode) and a few other components. Every element is connected to the 2-wire bus
epc100. Because every epc120 element has a unique address, the microcontroller has individual access to all bus components.
Each of the epc120 elements sends light, typically infrared light, focused towards a reflector or an object. It reflects the light back to the
photodiode. If multiple sensors like this would be operated in close proximity, scattered light from all sensors are probably reflected to the
receivers. This would lead to false triggering. Thus, a sequential operation mode has to be implemented. Basically, a master controller
activates one sensor after the other and reads back the status of each individual light beam.
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
Reference source not found for detailed information.
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epc120 with PD and LED
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Figure 4: System overview
6
➊
2-Wire Bus
Interface
(epc100)
Bus
1
, which is controlled by a microcontroller through an
50Ω, 100nF
Controller
Termination
Micro
Out
Bus
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Datasheet epc12x - V2.1
www.espros.ch
epc120