epc110
Functional Description
Light barrier applications
To cover different aspects of applications the epc110 device can operate in various modes:
1. Standalone mode
The LED flashes in a predefined/programmed cycle time.
2. Controlled mode together with a micro-controller
The LED pulse starts on the positive edge of the input EN. The light is detected while the enable signal EN is high.
3. Fix-parameter mode
This is the use of a pre-programmed parameter setting all the time. Usually the programming takes place during configuration and
test period of the board.
4. Ambient adaptive reading by dynamic parameters
In this mode the micro-controller is doing the parameter setting during the operation mode. For the communication the SPI interface
is used. For more technical details refer to chapter “SPI Interface“.
Application is for enhanced functionality and requirements as additional filtering of environmental ac light, adjustments of the
sensitivity on the fly, controlling the LED current by micro-processor, etc. Example of a sensitivity control: The photo diode current is
compared to two threshold levels. The result from the higher comparison ( OUTH) may be used to regulate the LED current as well
the photodiode receiving parameters appropriate to the environmental conditions.
Light barrier application without an additional controller
RStab
VDD
VDD
epc110
VDD33
RLED
OUTN
OUTH
OUTN
OUTH
PD
LED
C1
C2
GND
D2
D1
GND
Figure 3: Principle of standalone light barrier application
Figure 3 shows the epc110 in a light barrier application with minimal part count. The LED flashes with a predefined rate. If the current of the
light reflected (e. g. from a diffuse reflecting object or a retro reflector) to the photo diode at pin PD exceeds the threshold val ue IPDN, the output
OUTN goes to the low state for a time which is longer than the time to the next LED pulse. Thus, the signal at the pin OUTN is constantly low
when the photo diode generates a photo current which exceeds the threshold level. The stored flashing parameters of the LED can be
programmed using the SPI interface described in this manual.
The photo diode current is compared to two threshold levels. The result OUTH from the higher comparison level may be used to detect the
light reserve.
Light barrier application using a micro-controller
If additional functionality is required in a specific application, a micro-controller can be used. Such additional requirements can be power
saving modes, additional filtering of environmental ac light, counting purposes, etc. In this configuration, the LED emits one light pulse on the
positive edge at the pin EN. The photo diode bias and amplifier chain is enabled while the enable signal EN is high so a light pulse can be
detected.
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
6
Datasheet epc110 - V2.1
www.espros.ch
EPC [ ESPROS PHOTONICS CORP ]
